Perplexing 5.7GSI PEFS Fuel Problem Wont start - good fuel pressure & clean injectors

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
To me its strange that the ECM supplies the power to both of these but that is what it shows in the schematic. In earlier years it was supplied by the relay next to the fuel pump relay.

The fact that you were able to put some fuel into the intake and have it run indicates the coil is getting powered. Would still be interesting to see what that voltage is. Pulling off the connector is probably not the best way to test it though since it isn't being loaded. I would pull one of the connectors off the injectors and test the voltage there. That way the coil is still putting a load on the circuit


Okay. I have to wait for my ECM to come back now before I can continue with that diagnosis. Are you deciphering which way current flows/grounds by looking at the diagram, or by referencing the service manual and the wiring diagram? I assume the latter, since the diagram doesn't give much information.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
That purple wire going to the coil is the 12V INPUT going into the coil. The coil is NOT the power source.

Yes you are quite right why would they do it like that...

Has this boat rever ran well for you a mef4 on a mefi 3 that means someone burned a new tune for the engine and the harness kit...i
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Okay. I have to wait for my ECM to come back now before I can continue with that diagnosis. Are you deciphering which way current flows/grounds by looking at the diagram, or by referencing the service manual and the wiring diagram? I assume the latter, since the diagram doesn't give much information.
To me it looks like J2-32 is an input to the ECM of switches 12V power. Problem is that the circuit diagram doesn't show where this comes from.

The fact that the ECM powers on and that you have had the engine running with a small anount of gasoline in the TBI throat, means you likely have power also going to the injectors.
 
Last edited:

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
To me it looks like J2-32 is an input to the ECM of switches 12V power. Problem is that the circuit diagram doesn't show where this comes from.

The fact that the ECM powers on and that you have had the engine running with a small anount of gasoline in the TBI throat, means you likely have power also going to the injectors.



Bruce, I do have power to the injectors, since they do spray fuel. They just don't spray enough fuel. I've already ruled out absolutely every other possibility, except electrical. Now I know its not my ECM, so it must be a problem in power supply, or ground.

As far as I understand it now, I need to check my entire pink wire, and the tan wires, then the grounds from the ECM (again). If all of these are okay, and my ECM has 12v (which it does) then it should run. To be honest I am pretty skeptical that these tests will yield anything. I am very confused.

Tailgunner - my theory is the last MEFI III was ruined due to moisture. My boat has a stupid two piece engine cover, and the drains are located at the front, which is uphill. The result is that all the water runs through the center engine cover and all over the engine. I have a solution for this summer to fix that problem.

From what I am told, the two things that usually kill MEFI's is a voltage spike, or moisture problems.
 

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
The other odd thing I should mention is that the first time the key is turned on the the day, the alarm doesn't do the usual beep
Beep. It just stays silent, and the engine roars to life for 2 seconds then dies. Then after that it never starts again, and beeps most of the time.

Confusing Huh?
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
No when your alarm does not sound your fuel pumps will not work that is if your alram itself is working, I would call these guys below they do mefi3 to 4 conversion's you have some sort of ground wiring issue.

http://mefituning.com/
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
The other odd thing I should mention is that the first time the key is turned on the the day, the alarm doesn't do the usual beep
Beep. It just stays silent, and the engine roars to life for 2 seconds then dies. Then after that it never starts again, and beeps most of the time.

Confusing Huh?


Actually that's quite normal and the way its supposed to run...3 beeps system ok and she will start....if it beeps over and over you have a issue and a scanner should show the error code's you did not see any code's??????

Soft alarm is 1 beep every 3 second pause.. an beep...beep...beep.
 
Last edited:

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
Actually that's quite normal and the way its supposed to run...3 beeps system ok and she will start....if it beeps over and over you have a issue and a scanner should show the error code's you did not see any code's??????

Soft alarm is 1 beep every 3 second pause.. an beep...beep...beep.

Ever since I bought the boat, when I turn the key the bell goes "beep beep" with a small pause in between. Then it never comes back. I thought that was the "systems ok" beep.

Lately however when I turn the key, sometimes the alarm will not do its two beep sequence, but the fuel pumps still work.

It's never let an alarm out while running. And yes it had codes at one point, but they were erratic codes, in the wrong order, and some didn't exist, such as code 81. The first code it would read was code 43. One time though, not three. And then it was reading all types of crazy codes. But the ecm checked out fine at OBD II Diagnostics, so I guess it has to be some sort of wiring issue as Bruce said.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Ohh it is a wiring problem for sure and one other slight oversight evreything we have looked at is mefi3 stuff and mefi 4 has a different pinout so that might complicate things a bit or a lot.But the fundamental's are the same.
 

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
Ohh it is a wiring problem for sure and one other slight oversight evreything we have looked at is mefi3 stuff and mefi 4 has a different pinout so that might complicate things a bit or a lot.But the fundamental's are the same.

Ok so here is my conversion harness. The first pic is the mysterious unused connector, for which I have a male 10 pin connector that plugs in, and has two fuel pump style male/female leads branching off it. The confusing part is that the only wire with power is the wire I am pointing to. However the connector I have for it only has one pin in it, and its on the opposite side. So basically this is unused, since I cant find a home for it, and it wouldn't matter anyway since its dead. I just wonder what this is for. Is it possible that my standard DLC connector will not work now with this conversion kit? I do get code 12 three times, and I hear the solenoids energize when I put it in service mode, so I think I answered my own question. I guess this is just a connector for another application.

image2 (1).JPG

image1 (1).JPG

Here is my plan :

Once the ECM comes back, I will check the pink injector wires for 12V when ignition is on and/or cranking. Then check tan wires for resistance. Then if these check out, I will trace the pin on the boat engine harness, to this stupid conversion connector, which as you can see has no color coded wiring. Then I will verify that the ground continues all the way through to the ECM.

If those tests show I have 12V to my injectors, and ground the the ECM, and the injectors are STILL pulsing, but not enough fuel, then what else could it be?

I was thinking maybe I should draw up a diagram of this conversion harness, and probe each wire, then label/draw them on my diagram and on the harness. Then I could easily use the wiring schematic from my engine to identify each pin on the male side of the conversion harness, since it plugs into my old female connection which used to plug in to the MEFI III. Then at least I, as well as anyone else on the fourms needing a diagram would know which wires are active in this stupid conversion harness.
 

Attachments

  • image2 (1).JPG
    image2 (1).JPG
    94.6 KB · Views: 0

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
My ECM is back - but my fuel pump is apart on the work bench waiting for new o-rings. I will post the final sizes once I have figured them all out. I used another topic on these forums to pick o-rings, but they were off a little bit.

Can I test for power at the other wires with the fuel pump disconnected? I think so but I was just wondering what you guys think. The o-rings wont be in till Thursday.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Well here is what you have going on a mefi 4 ecu running a mef 3 component setup..the only thing i can tell is its been repinned and the mefi4 has 2 more grounds you need to find a schematic to understand how this is done and its done quite often. And one more thing the mefi 4 module has bee reprogrammed to fit your engine or better said tuned to your engine...was that done right.... there is no way to know for now...that is why i asked you if this boat was ever running right in your possession. For now find out the pin out diagram for the conversion and then follow it down i posted a site link where they do this type of work and should have a pin out.

http://www.gmpartsdirect.com/result...ber=88963118&singlepart=1&partnumber=88963118

Theres the harness you have now i cant find a wiring diagram
 
Last edited:

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
Well here is what you have going on a mefi 4 ecu running a mef 3 component setup..the only thing i can tell is its been repinned and the mefi4 has 2 more grounds you need to find a schematic to understand how this is done and its done quite often. And one more thing the mefi 4 module has bee reprogrammed to fit your engine or better said tuned to your engine...was that done right.... there is no way to know for now...that is why i asked you if this boat was ever running right in your possession. For now find out the pin out diagram for the conversion and then follow it down i posted a site link where they do this type of work and should have a pin out.

http://www.gmpartsdirect.com/result...ber=88963118&singlepart=1&partnumber=88963118

Theres the harness you have now i cant find a wiring diagram



Thank you so much for all the help. I just said screw it an put my fuel pump back together today, threw the computer in, and started doing checks. Below is a list of what I checked today.

Battery voltage at injectors - Good
Injector resistance 1.5 Ohms - Good
Injector ground wires to end of MEFI III harness - .3 Ohms - Good
Injector ground wires through conversion harness - .2 Ohms - Good
Ignition module ground through both harnesses - .3 Ohms - Good

Then I tried to start it, and got the SAME result I always do. The engine roars to life for 2 seconds, then cuts out just as quickly as it started, and never starts again. If I wait 24 hours it will do that again.

I then changed the ignition module and coil - no change in condition.

Checked codes again (realized I have been reading them incorrectly since it only has to flash codes twice, not three times). I got codes 34 - Map Low, 41 ignition circuit open, and 81 (which I have no idea what it is). I did disconnect the knock sensor today while cranking, thinking maybe its detecting knock, could that throw code 81?

Code 34 is probably due to me disconnecting the map again. Code 41 is probably due to me forgetting to reconnect the ignition module leads after installing it, and then trying to start it. Code 81 from what I understand can be tons of things, from no oil pressure, to bad injector drivers. Seeing as OBD Diagnostics just confirmed my ECM is functioning, how do I find out what code 81 means?

I ran out of daylight, but I am going to clear the codes again tomorrow, and then try like hell to get them to reappear, but without me disconnecting any sensors.

Honestly guys, I am getting desperate. Is there a way to rule out any bad sensors, like the oil pressure sending unit (which is brand new), or the MAP?

Is there a possibility that OBD Diagnostics tests falsely flagged my ECM as good, when in fact it is not?

Again, just to recap, it was running perfect last fall. I pulled the engine to do an oil pan, and other misc items. The engine runs if supplemented with fuel, and has good compression, so its not mechanical.

And Tail Gunner, I have checked all the MEFI 4 grounds, I noticed that it has one extra ground as well.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
You have put a fuel pressure gauge on the high side while cranking the engine to see a constant 30lbs. Just because it powers up doesnt mean its holding 30lbs

http://www.pirate4x4.com/tech/billav...510005P%29.pdf

Page chapter 5 page 1...You have your work cut out for you..

Page chapter 5 page 36 pinout's

Page chapter 5 page 56...:facepalm:
 
Last edited:

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
You have put a fuel pressure gauge on the high side while cranking the engine to see a constant 30lbs. Just because it powers up doesnt mean its holding 30lbs

http://www.pirate4x4.com/tech/billav...510005P%29.pdf

Page chapter 5 page 1...You have your work cut out for you..

Page chapter 5 page 36 pinout's

Page chapter 5 page 56...:facepalm:


As I checked this for responses I was on page 56. I think I need to use an MEFI III diag manual, since some of the sensors referenced in the IV manual I do not have, such as crank position.

I did verify that its holding pressure at 30 PSI while cranking. It doesn't drop at all under any condition.

Is there any sensor that can cause this to happen? I seriously still think its the damn ECM. I guess I need to buy the Diacom tool now don't I? Wait times for Volvo Penta tech's in the CT area are outrageous right now since the season is just starting. I will not miss memorial day another year because of engine problems. This needs to get resolved. Should I just bite the bullet and buy the damn scan tool?
 

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
Also, the more I read, I bet my code 81 is for the injector drivers, but only because I was cranking with the leads disconnected so I could test for voltage drop. I saw a voltage drop from 12.5 to 10.5 at the injectors while cranking. That seems normal. I truly think all three of those codes are due to me cranking with items disconnected, but I cant confirm that.
 

nunnink23

Seaman Apprentice
Joined
Apr 27, 2015
Messages
31
Should we play the sensor game? I put all the sensor names in a hat, and you pick one? I started this morning with a new MAP sensor. It will be in on Friday.

If I cant figure this out by Monday, I think I am ordering a Diacom tool. At least that tool will have some resale value when I eventually move on from this boat.

Is it possible my TBI isn't working correctly? I had the injectors checked by two people now. The first company rebuilt them, the second tested them. I rebuilt my TBI.... They are so simple I cant imagine I messed something up. In fact, I have rebuilt it three times now. Once to verify that I didn't make a mistake. Third because I needed to have my injectors tested. They are not leaking.

Is it possible that I would see 30 PSI of fuel pressure on the inlet side from the fuel pump, but the fuel pressure is escaping the TBI through the diaphragm? I thought that it would never build 30 PSI if the diaphragm was not working, because the fuel would just pass through the TBI and back to the fuel cell in an endless loop? The injectors can only be installed one way, so those aren't wrong.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Testing your map although this is a car the test is identical and use's a 5 volt rail as you already are aware of. A map actaully controls the pulse width look in that mefi 3 file i posted i believe the actual volts to vacum are in there.

 
Last edited:

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Not marine again but it illustrates how to check low voltage what works and what doesnt..page 3 The tbi is the same operation principal in auto or marine.

http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf


1. Engine cranks but will not start. There is an assumption that the battery is at a full state of charge, the fuel tank has fuel in it and that all sensors are correctly connected and there are no trouble codes in the ECM. 1. Does the injector spray fuel when cranking the engine? Yes ? Go to step 2. No - Remove one of the injector connectors from an injector. With a voltmeter or test light measure the voltage or validate power to the pink wire of the connector with the key on. Yes ? Pink wire has voltage, go to step 1a. No ? There is no power getting to the system. Check for proper connection to the battery, fuses are good, relays have been connected and seated properly. Correct the power issue; if there is still no fuel spray when cranking the engine after this has been corrected go to step 1a. 1a. With the voltmeter or test light still connected crank the engine and verify voltage to the pink wire on the injector connector. Results: ?0? volts or the light goes out when cranking the engine. The primary (pink) ignition wire is incorrectly connected to the vehicle. This is to be an ignition 1 (ING1) source which is power in both the key run and crank position. Correct the connection of this wire and verify voltage to the pink wire on the injector connector. Test again for fuel spray during crank. If the engine still cranks, is spraying fuel, but will not start go to step 2. ?Low volts, < 8? This is an indication of either a battery in a state of very low charge, a bad battery or too much resistance in the system. -record the battery voltage while cranking at the battery. -record the voltage at the pink wire of the injector connector while cranking the engine. -compare these two voltages, they should be within .2 (2/10) volts of each other. If these voltages are greater than .2 there is a bad connection or too much resistance in the wire feeding the ECM. -Correct the issue with low voltage. If cranking voltage is above 9 volts while cranking and there is still no fuel spraying the issue is in the fuel delivery system. ?9 volts or higher? this is normal cranking voltage. If there is no fuel spraying while cranking the issue is in the fuel delivery system or ignition system Trouble shoot the fuel system for improper operation (See Fuel System checks at the beginning of this guide). Troubleshoot ignition system, go to 1b. 1b. Your TBI fuel injection system fueling is ?triggered? from the ignition system. It is assumed that the coil is operational, a 12 volt ignition 1 (IGN1) source is connected to the positive terminal of the coil for external coil applications or to the positive slot for coil in cap applications. Remove plug wire and check for spark while cranking. No Spark ? Repair ignition system. Has spark ? Insure wire continuity between the ECM and the distributor or tach Filter. If fuel is still not spraying go to fuel system troubleshooting before replacing any components. If all wires are in tact and routed correctly and all fuel system checks are correct, replace distributor module or tach filter. 2. Perform the fuel system checks found at the beginning of this troubleshooting Guide. If the fuel pressure and fuel system are operating as required Insure that the check engine light is on with the key on but the engine not running and there are no stored codes (except for code 42 if you have just set the ignition timing or code 12). If you have installed a new distributor, removed the distributor for any reason your ignition timing may be off too much to operate the engine properly. Disconnect the connector(s) from the injectors and set the ignition timing to its proper setting while cranking the engine. Assumption here also is that the timing mark on the balancer is lined up with TDC of #1 cylinder and that the distributor is seated properly and not 180 degrees off. If all of this checks OK go to step 3. 3. Measure the voltage on the throttle position sensor. If using a scan tool you can read TPS, if not measure the voltage. To measure the throttle position voltage check between the brown wire and the black/white striped wire on the TPS with the TPS still connected and the key on. DO NOT PUNCTURE THE WIRES to measure this voltage and only use a digital voltmeter. Voltage can be measured by back probing the TPS connector between these wires either with a thin paper clip or appropriate tool used for this type of measurement. If you have gone through all of the above procedures and the engine still will not start you will need to call tech support. In many cases the specifications of the engine are different than what was originally discussed or assumed. When you call tech support you will need to have the following information available. Fuel pressure at the inlet of the TBI unit________________________________ Return line fuel pressure____________________________ Voltage measured at the battery while cranking___________ Voltage measured at the pink wire on the injector while cranking____________ Voltage measured at the TPS sensor key on engine off_____________________ Codes stored in the ECM Any information that you feel is important for diagnosing the issue at hand. 2. My engine is running to lean, or is backfiring on
 
Top