Volvo Penta 5.7 GXi-C cranks but won't fire

[muc]

The OP's link in previous post and my manual shows the same

OK, I see the 5.1 volt and I'm not sure where they are getting that number for Depspower because I'm pretty sure that's a battery voltage circuit. Could be a typo or could be my memory ---- long time since I've worked on a MEFI system.

Part of the problem is your using the scan tool diagnostics section of the manual without having been directed there by the scan tool. I'm trying to remember back to the days of diagnosing based on trouble codes and I seem to remember that if you get a DTC 81 you should start with the first DTC 81 flow chart and Despower is the last in line for testing ---- unless directed there by the scan tool.

I'll be honest that I don't use those troubleshooting flow charts. At the factory schools they tell us to understand how the system works and troubleshoot based on that. And for the hands on tests they "bug" the engines in the test cells so that if you use those flow charts you will either take too long or come up with the wrong diagnosis.

I advise the young techs to read earlier part of the manual to get an understanding of how the complete system works.

If you are going to try to use those charts, I recommend you start with the first chart DTC 81 - Crankshaft Position Sensor (CKP) and after looking at that chart, they seem to be talking about battery voltage?

Maybe do the 2 tests I recommended and post the numbers?

I do know that 0.14 volts on the 5v ref is way too low and points to a short to ground. Read page 13 of the manual to see why.

 

[muc]

Thanks Muc. This should be easy enough to measure. I'll report back after these two measurements have been obtained. On the assumption that I do get the desired 5V at the TPS & 12V at the CKP plugs, would there be a consensus as to sending the ECM out for an incoming test?

I don't know what they test when you send out the ECM. Never done it. If it was me, I would put that money towards a scan tool. Then you can "test" it yourself.

Also, what if they find a bad circuit and repair it? Maybe the damage was caused by the engine wiring? What happens when you plug the repaired ECM back into bad wiring? This is why you never swap a known good ECM onto the bad engine, you put the bad ECM on the good engine. Much less chance of messing something else up. I have had a twin engine boat come to me with two bad ECM's because the customer and his buddy's started swapping parts.

 

[PcolaBeach]

Don't know how much I can help with this because I would only use a scan tool. But I'll try.

J2-2 should have 5v +or- .2v
J2-17 should be battery voltage

Not sure how your measuring J2-2 and J2-17 but here is how I would do it without a scan tool.
Unplug MAP, TPS, 2 wire temp sender, CAM and CKP. Make sure all 5 are unplugged.

key on
+ voltmeter lead to A in TPS plug, - voltmeter lead to B in TPS plug. Should see 5 volts.

key still on
+ voltmeter lead to A in CKP plug, - voltmeter lead to B in CKP plug. Should see battery voltage.

So, following Muc's suggestions from above, at the boat today measured:

5.03v at the Throttle Position Sensor harness
5.03v at the Manifold Absolute Pressure Sensor harness

11.33v at the Crankshaft Sensor harness
11.22v at the Camshaft Position harness

Battery voltage was 12.28

Resistance among all 6 wires between CKP/CMP harnesses and disconnected J2 harness were 0.2 ohms each

Batteries On, Key On ECM J1-6 to Fuel Pump Relay 85 circuit fails to close to ground and energize fuel pump motors

DTC - 81 still present

 

[muc]

Ok, you have done a no load voltage test.
Depspower failed with no load. I would assume that it would only get worse with a load (CKP and CMP) plugged back in.
5v ref passed no load. But you posted about a 0.14v measured under load?

It seems that you have a voltage drop issue. That problem is almost always in the wire harness.
The next step is to find out if it’s on the power side or ground side. I’m guessing that it will be on the ground side, because based on my reading of your posts the ECM is trying to ground the fuel pump relay but can’t.

A couple of questions
Is your VOM up to this job? This does require a “good” meter. Most $200 or cheaper meters aren’t capable of this task.
Ohm’s testing probably isn’t going to cut it for this job. You will most likely need to switch to loaded voltage drop testing.
Is time to get scan tool to work on this?

When you last checked for codes. Had you plugged everything back in and cleared the codes before checking again?
The times we tried to clear codes with a paper clip in school it was kind of hit and miss on it working. The instructor had us do this to drive home the point that troubleshooting these engines is a waste of time without a scan tool.


Is it possible to find a comparable engine to pug this ECM into?

 

[Fun Times]

Batteries On, Key On ECM J1-6 to Fuel Pump Relay 85 circuit fails to close to ground and energize fuel pump motors

Though I don't have or couldn't find a/your Volvo Penta service manual for a wiring diagram to confirm this but another consideration for the fuel pump relay activation that hasn't been mentioned is it seems you haven't tested for any +power of the ignition feed circuit number 439? between the ECM J2-19 to #86 of the relay which should be a pink wire ?.

Which you mentioned you had a quick power up while connecting up a number of wire plug connectors which should help indicate you have a bad wire connection someplace not waking up the fuel pump, ecm, etc. etc. until the wires are moved just right it seems. Could be power or ground and all wires ought to be wiggled with the key on....Also on some units there has been known to be a internal delay in-between fast key-ups to where it may not turn on the fuel pumps or warning horn so you may be experiencing that as well.

Where is the new ECM that may have been tried? < If it's true a proper matching good ECM was test then it ought to lower the theory some that the ECM J1-6 isn't sending it's signal to #85 and in turn #86 may not be getting the correct ignition key/wake-up power it needs.

As mentioned I don't have your manual to work off of so I'm only guessing that this MEFI 4 manual of a different marine engine manufacturer can help with a general guide of my thoughts...Page 162.., http://www.readbag.com/marinepowerusa-pdfs-marinepowerusa-5-0l-5-7l-mefi-4-service-manual

^ Plus I ran across where Muc mentioned the same for J2-19 back in 2013 needing good power.:encouragement:, https://forums.iboats.com/forum/eng...ta-5-7-gi-e-ecm-problem?p=6574946#post6574946

 

[PcolaBeach]

Ok, you have done a no load voltage test.
Depspower failed with no load. I would assume that it would only get worse with a load (CKP and CMP) plugged back in.
5v ref passed no load. But you posted about a 0.14v measured under load?

It seems that you have a voltage drop issue. That problem is almost always in the wire harness.
The next step is to find out if it’s on the power side or ground side. I’m guessing that it will be on the ground side, because based on my reading of your posts the ECM is trying to ground the fuel pump relay but can’t.

A couple of questions
Is your VOM up to this job? This does require a “good” meter. Most $200 or cheaper meters aren’t capable of this task.
Ohm’s testing probably isn’t going to cut it for this job. You will most likely need to switch to loaded voltage drop testing.
Is time to get scan tool to work on this?

When you last checked for codes. Had you plugged everything back in and cleared the codes before checking again?
The times we tried to clear codes with a paper clip in school it was kind of hit and miss on it working. The instructor had us do this to drive home the point that troubleshooting these engines is a waste of time without a scan tool.

Is it possible to find a comparable engine to pug this ECM into?

Good stuff Muc .... Appreciate your response! I'll try to address your questions:

Previous Depspower & 5V test results posted in the .pdf files were with the J2 harness disconnected. The corresponding test results from yesterday were following your test suggestions. I have not tried to backprobe the depspower or 5v harnesses to test under "load". Access is tight to get to the Crankshaft Position harness so obviously, getting set up to back probe this sensor would be tricky.

The VOM meter I'm using is a Fluke 85 III. I don't have a merger tester.

I'm real glad you asked about clearing codes. I have tried a handful of times to clear the codes with a paperclip, throttle position, key, etc. and to your point, I've never been successful in clearing the codes so I see your point.

We're not likely to have access to another comparable engine to plug this ECM into. However, the owner is considering purchasing a scanner tool. Rinda and OBD Diagnostics appear to be two of the better manufactures. We'd appreciate any input on what scanner would best suit our purposes for both diagnosing this issue and periodic engine health testing.

Thanks again for your interest and involvement.

 

[PcolaBeach]

Though I don't have or couldn't find a/your Volvo Penta service manual for a wiring diagram to confirm this but another consideration for the fuel pump relay activation that hasn't been mentioned is it seems you haven't tested for any +power of the ignition feed circuit number 439? between the ECM J2-19 to #86 of the relay which should be a pink wire ?.

Which you mentioned you had a quick power up while connecting up a number of wire plug connectors which should help indicate you have a bad wire connection someplace not waking up the fuel pump, ecm, etc. etc. until the wires are moved just right it seems. Could be power or ground and all wires ought to be wiggled with the key on....Also on some units there has been known to be a internal delay in-between fast key-ups to where it may not turn on the fuel pumps or warning horn so you may be experiencing that as well.

Where is the new ECM that may have been tried? < If it's true a proper matching good ECM was test then it ought to lower the theory some that the ECM J1-6 isn't sending it's signal to #85 and in turn #86 may not be getting the correct ignition key/wake-up power it needs.

^ Plus I ran across where Muc mentioned the same for J2-19 back in 2013 needing good power

Thanks Fun Times ... For this engine, It looks like power to J2-19 (Pink/White wire) comes from Ignition Relay #87 once the ignition key has been turned on and 30 to 87 'makes' at the relay. Testing for Voltage at J2-19 with the harness disconnected and key on should be easy enough. This reading should be the same as battery voltage.

 

[Fun Times]

Gotcha on the differences to the number of relays and how they're wired up, etc..

So speaking of Relays I saw where you ohms tested the relays and thought they seem fine but sometimes they do get sticky internally and won't activate properly every time.

Next time you're in the boat with the key on try mildly rapping on all the relays to see if they power up the fuel pump, warning horn, etc...Also see if they'll all inner-swap with each other to see if something changes state ultimately it would be worth try new relays as again they do fail internally and won't come back to life.

Again carefully wiggle, shake, push in, slightly twist and visually inspect all wire pins, connectors, etc., with the key on to see if something powers back up...Again.

Ask the owner if there was ever a fuse that failed on the engine? If fuse F1 or F2 ever blew out then it is recommended that both fuses be replaced and not just the 1 bad one...That info ought to be on the fuse box lid/cover by the fuse/relay diagram if I recall it correctly.

 

[muc]

Good stuff Muc .... Appreciate your response! I'll try to address your questions:

Previous Depspower & 5V test results posted in the .pdf files were with the J2 harness disconnected. The corresponding test results from yesterday were following your test suggestions. I have not tried to backprobe the depspower or 5v harnesses to test under "load". Access is tight to get to the Crankshaft Position harness so obviously, getting set up to back probe this sensor would be tricky.

The VOM meter I'm using is a Fluke 85 III. I don't have a merger tester.

I'm real glad you asked about clearing codes. I have tried a handful of times to clear the codes with a paperclip, throttle position, key, etc. and to your point, I've never been successful in clearing the codes so I see your point.

We're not likely to have access to another comparable engine to plug this ECM into. However, the owner is considering purchasing a scanner tool. Rinda and OBD Diagnostics appear to be two of the better manufactures. We'd appreciate any input on what scanner would best suit our purposes for both diagnosing this issue and periodic engine health testing.

Thanks again for your interest and involvement.

Might be easier to measure at the CMP?
Back probing is kind of frowned upon due to how easy it is to damage the seals/wires. Be careful. Is possible a previous repair person might have done this and that’s what is causing problems now? Are you in a salt water environment?

As far as recommendations on scan tools. I have only used the tools that are recommended by the manufacturer. For Volvo that is.
Laptop based
1. Vodia 5. This is a dealer only set up and the tech must pass tests to unlock the different parts of it.
2. Rinda Diacom. This is available to anybody and is a very good program.
Stand alone handheld.
1. Vodia. Didn’t like this one. It would do the job but was a pain to use. Dealer only, locked. No longer made
2. VP 2000. Made by OTC. Loved this one. Only worked on MEFI. Dealer only but wasn’t locked. No longer made.
3. Rinda Techmate. This is also available to anyone, it works Ok. It’s my last choice due to the limited amount of data that can be seen at once. But is more than capable.
4. Rinda Techmate Pro. I haven’t used this one but I’ve been told that it displays more data on the screen. Should be more than capable.

You have a MEFI ECM and they weren’t very “smart” so I would think that just about anything that will read it would work for you. There was somebody posting on this forum that had something that was almost free. I don’t remember his name, maybe somebody else does?

 

[muc]

Clearing codes.
If it is a hard fault that is present at key on, you won’t be able to clear it.

 

[Fun Times]

You have a MEFI ECM and they weren’t very “smart” so I would think that just about anything that will read it would work for you. There was somebody posting on this forum that had something that was almost free. I don’t remember his name, maybe somebody else does?

Maybe DouglasW ? as I think he mentioned being an internal computer builder specialist when discussing past EFI stuff, https://www.iboats.com/user/douglasw

 

[PcolaBeach]

Thanks Muc & Fun Times for your responses and input.

I'll check the J2-19 voltage next time at the boat. The owner did replace the fuel pump & ignition relays in the last week with no change. As far as the 20A F1 & F2 fuses, although they've tested fine, we'll likely replace those as well.

Rinda Diacom and Rinda Techmate Pro were the two scanning tools being considered. Clearly there are advantages and disadvantages to each as far as portability, information gathering, learning curve, etc. For what we're up against, it seems like the Techmate Pro should get us what we need especially considering it's a non-running engine.

The boat operates in a saltwater environment and is raw water cooled. Rather than back probing which I agree is risky, I'd probably look for something comparable to Volvo Penta's J 35616-A Connector Test Adapter Kit to obtain any loaded readings. I have seen one wire at the 8 wire relay panel harness (top row 2nd from left) that had been probed with a needle probe. The insulation on the wire was nicked open maybe a 1/16" exposing the wire. I don't remember the colors although I do recall ohm checking the wire's resistance from the relay terminal back to the J connector and not finding a high resistance.

Possibly related to what appears might be a ground issue causing many of the problems, the trim/tilt up relay was found failed with a blob of melted plastic about the size of a pencil eraser on the relay body. Neither the 10A or 50A fuse had tripped. Could still hear the trim motor run for trim down although when the trim down relay was removed and placed in the trim up position and testing at the switch the motor did not run for trim up. At first glance, the trim circuit looks more or less isolated until I notice B+ and B- harness right in the path. Intend to disconnect, test and reconnect that harness as well. We'll be installing 2 new relays this week sometime.

Might also do some voltage drop testing from the batteries to different ground setups with the cables off at the battery. I have observed the port side lower rear ground lug does not appear to be in very good shape. So much so, I've been reluctant to even put a wrench on it and loosen the ground stud nut.

Really have to give it to those of y'all that persist with finding and correcting troubles on your engines. A tolerance for heat and contortionist skills seem to be right up there with technical skills.

Thanks again ...

 

[Lubak572]

I have rinda, I would get mefiburn. I still may.

 

[PcolaBeach]

So, as a follow up, measured voltage at J2-19 was the same as battery voltage. Owner is beginning to shift gears towards relocating his boat to a local shop that specializes in VP engines. Objectively, the fuel pump relay ground contact 85 to J1-6 circuit is not reliably being commanded closed to ground by the ECM. That being said, it remains an unknown if this is because of a "problem" with the ECM, a separate permissive issue the ECM is sensing that results in the ECM electing to not complete the ground circuit for J1-6 to FP relay contact 85 or some other unknown issue.

 

[alldodge]

Only problem with shop, is most run thru the checks, then replace parts an move on, time is money. Don't know if they would be willing to send the ECM off to see if it can be repaired. Either way, understand and hope we get to know the final outcome

 

[PcolaBeach]

Very good. Yes, whenever the final cause/solution becomes known, I will follow up with the forum.

 

[89sandman]

Have you ever checked for "strobe" at the injectors. On page one it lists fuel injector driver problems as one of the possibilities of the code. The drivers for the injectors are in the ecm...

 

[Fun Times]

So, as a follow up, measured voltage at J2-19 was the same as battery voltage. Owner is beginning to shift gears towards relocating his boat to a local shop that specializes in VP engines. Objectively, the fuel pump relay ground contact 85 to J1-6 circuit is not reliably being commanded closed to ground by the ECM. That being said, it remains an unknown if this is because of a "problem" with the ECM, a separate permissive issue the ECM is sensing that results in the ECM electing to not complete the ground circuit for J1-6 to FP relay contact 85 or some other unknown issue.

It's good to know you ought be getting 12v wake up power as far as the ECM.

Your theory of J1-6 not sending the activation ground signal is very probable for cause and you ought to be able to test some of that theory by adding your own temporary ground wire circuit of that side / # of the relay and see if the fuel pumps, etc. activate...Also try using your Fluke Multimeter and measure that line circuit.

But first lets sort of back up to posts 23 and 24 for a bit to where Muc has you checking battery voltage readings and battery voltage drops of all the + and - wires along with the main battery cables for lost power connections via a connection drop of either side.

https://forums.iboats.com/forum/eng...cranks-but-won-t-fire?p=10747400#post10747400

11.33v at the Crankshaft Sensor harness
11.22v at the Camshaft Position harness

Battery voltage was 12.28

While 12.28 could be considered exceptable to certain degrees of getting the engine to start while everything else is under normal working conditions, 'The voltage you're at right now is just a bit on the low side as 12.6/12.7 volts would be more ideal to have for a healthy starting system especially knowing something isn't quite right evident with the other engine accessories are showing under 12v at 11.3ish volts. Those numbers ought to be closer to match the health of the battery volts...Also try checking the battery cold cranking amps as they should be around 600+ at a minimum.

Try charging up the battery some and see if the lower numbers improve some on the engine accessory components including the engine starter, back side of the alternator on outwards to the sensors, etc..

At this point I definitely agree that while some service shops do take the time to fully test things over such as you are doing, some other service shops out there may just try a few parts, some general testing and get where they get and call it a day done or not.

You seem to be very thorough and methodical with an understanding of how these systems ought to work plus the fact you keep coming back with what seems like you are narrowing in on the issue and we're doing our best to stay with you until something gives.:eagerness:

Reconfirm your talks about them trying another ECM and where did it go, can you try the other ECM again, etc. etc..

Give these few things Muc suggests and maybe re-read the topic to see if something may have been missed along the way before turning it over to someone else.

I believe you've got this! :encouragement:, Good luck.

 

[PcolaBeach]

Have you ever checked for "strobe" at the injectors. On page one it lists fuel injector driver problems as one of the possibilities of the code. The drivers for the injectors are in the ecm...

A Noid light was used by a previous marine tech at the fuel injectors and although I wasn't there to witness, he was evidently successful in seeing the light strobe as the engine was being cranked.

I appreciate the comments of encouragement and will likely be making a few more checks before the boat ends up in the shop.

Going back to my notes from Post #9 Item 2 ... Resistance measured from the fuel pump relay terminal #85 to ground was a.) infinite with key off and b.) 0.420 megohms (420 K-Ohms) with key on. I find this interesting that even though the resistance did not go to zero, the ECM was 'attempting' to close to ground given the reading change. Under initial actions #9, continuity tested SB/Y wire from fuel pump relay terminal 85 to J1 connector pin 6 found as 0.2 ohms.

I might try disconnecting the 8 wire harness at the front of the fuse/relay panel, create a circuit from the black/yellow wire at the harness to ground and re-test with the ignition key off and then on. The intent here is to see if there is anything going on within the fuse/relay panel that is negatively influencing the full ground making it to the fuel pump relay contact #85.

Also would like to give each of the harnesses some serious wiggle action with the key on to see if by some miracle the fuel pumps run.

 

[89sandman]

Is it possible to open up the ecm and check to see if one of the capacitors has a leak. Usually easy to see, the
"legs" of the capacitor will be black from the leaking and sometimes the board itself will be stained in that area. Have you ever tried hotwiring the fuel pumps and trying to start it?