1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly fuel?

cc190cc

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Hello,

I have a 1994 Volvo Penta 5.7GI, this is a TBI motor. I searched all of the stickies and other posts before asking this question. I bought this boat with a blown motor and replaced it with a rapidmarine long block over the winter. Got it running and it idles well, and runs pretty well at low RPM. The boat is in the water in a slip now so im hoping to fix this problem on the water. The problem im having is around 2k rpm it starts to fall on its face, sometimes it will rev up to 2300 or right around there but that is it. If i stay in it the engine will stall sometimes...then start right back up and idle fine. I have a couple of things that I think could be issues, I am going to list them below, any feedback would be appreciated, I know everyone is busy trying to go boating themselves.

1. The old motor had two oil preasure sensors or switches. One towards back of intake mani. and one in side of block right above the oil filter. When i was switching over parts the one on the side broke and I was having a hard time finding an identical replacemetn. I started the motor with one of the sensors (one on back of intake) and the guage works, good oil preasure, but it bounces sometimes. I read somewhere that not have the second oil preasure switch can cause issues.

2. When its running and i unplug the map sensor the performance does not change. This makes me think that maybe its running off factory presets or something, doesnt seem to be in limp mode cuz it does rev a little past 2k. I changed the map sensor and it started to run a little more rich while cold, but didnt change anything else really.

3. I am 80% sure the timing is correcct. I know its supposed to be at 8 degrees btdc. While running with the light on it the mark is right around 8. This engine has two diagnostic plugs on the engine, and ive jumped the two wires on the larger plug before setting the timing. Does anyone have thorough directions on how to set the timing on this, I believe it is different than the EST distributor with the shunt. Don I know you will probably be reading this and you directed me to your stickie last time, but that was for a carb model and i believe it is different because both plugs on my distributor are used and if unplugged i do not believe it will run. .

4. When i purchased the boat it had about 80 gallons of gass, i added stabalizer last fall and topped it off yesterday before putting it in water. It has approximately a 100 gallon tank. The fuel pump on the front of the engine is a bit noisy, i changed the filter before starting it. Should I add a lot of dry gas, stabalizer or octane booster??

5. When starting it yesterday and ran really rich and a bit rough, this cleared up witin about 5 minutes.

Any feedback is appreciated, I really appreciate all you guys do on here for basically free.

Chad

5.
 

sqbtr

Senior Chief Petty Officer
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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Are you sure the model # is complete. My info shows a 5.7GI as being multipoint inj.
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Sorry, yes it is correct, the engine cowel says Volvo 5.7 GI, the book says its a 5.7 GI PMDA. I can take any pics or videos necessary this evening, it is definately a TBI motor.

Chad
 

Don S

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

The rest of the model number (PMDA) tells us what it is. Besides, TBI is the only injection method used by Volvo in 94.
To many possibilities to list, but here is the troubleshooting chart that outlines what to check, and here is a link to the OEM manuals. The EFI Diagnostic manual is the one you need to look at for this problem.
http://www.4shared.com/dir/14518511/785d67cc/MDsharing.html


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cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Don, thank you very much, I really do appreciate your help. I will go through the information you provided and will let you know how i make out.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Hello,

So I spent about 6 hours troubleshooting today, spent about 1 hour going through manual you provided Don. I am still having the same problem but have some new information to provide. I checked the fuel pressure on the fuel box(low pressure pump) and it was right aroud 8 psi, the pressure on the line coming out of high pressure pump was right around 10-11. When i rev the engine up the high pressure would go down to about 8-9 psi. When i just turn the key to the on position the high pressure pump is very noisy, the guage will go up to about 10-11 psi and then drop down to 0, same on the low side, it will build up while the pump primes, then drop to 0. Replaced fuel pressure reg. though did not fix problem.

When you start the engine and rev it for the first time it sounds awesome, opens right up, sounds perfect. It is not in RPM reduction mode. Every time you try to rev it after that it falls on its face, bog, if i hold throttle open to much it will actually stall. The pressure also drops down a few PSI while this is happening.

I changed the fuel filter again today, checked the anti siphon valve which appears to be electronic (3 wires, red, white, black, power at red when key on), I could blow into it and suck fuel through it though did not feel anything while like a solonoid when turning key on off.

When i unplug the low pressure pump the engine runs for about 5 seconds and then dies. WHen i unplug high pressure pump engine immediately dies, high pressure pump (pump near fuel box) very noisy.

I spent a lot of time on this today and am getting a little frustrated. Does the fuel PSI seem to be ok, and should it maintain pressure during the prime.

Im thinking that it revs good on the first try because it was primed before starting, then once it runs out of fuel from prime seems like maybe the pumps cant keep up.

Fuel pump..pumps???

Don what do you think man, what should I try next. I have also checked the timing, wires, plugs...im pretty sure its a fuel issue just because it runs perfect during the first rev and then appear to be leaning out. I pulled a plug and they looked decent. Looked like may be running bit lean.

I have a video of engine running and being problematic, would it help.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Also,

Im not sure that i would classify this as a surge. The engine runs perfectly smooth at idle all the way up to about 2-3 rpms. Though if i punch it it will just fall on face, if i ease into, it will fall on face around 2-3k. All testing performed above was done free reving, not under load.
 

Don S

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

When you replaced the fuel filter, do you check the old one or water? It's the only way you will know if you have water or not.
Hook it up to a diagnostic computer and see what's going on.
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Don,

Did the fuel pressure i described above seem ok, 8psi on low 10-11 psi on hi side? I tried to find the specs for the shrader valve psi though didnt have much luck, I think I am going to give it one try today with external tank, should only take a couple minutes to hook it up.

If that doesnt work ill have the marina where the slip is, try to scan it on Monday.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Hello,

Ok, today i eliminated the following (bad gas, water in gas, clogged filter, map circuit, map sensor, tps circuit). Below is video of it running, you will hear the hesitation when i rev it. Though this video does not demonstrate it very clear, if i shut the engine off for 5-10 min and restart, i can punch the gas and it opens right up, runs perfect. If not for this I would think timing issue, im leaning towards high pressure pump. Pressure on high side was about 10-11 psi, dropped a few PSI while reving. Below is the video, let me know what you think.

I can have this scanned probably this week but i believe map and TPS already eliminated.


Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Hello,

Oh and by the way, replaced the fuel pressure regulator last night because it was extremely rusty. I did not think it was the problem but the visual inspection was bad, if it was not bad it would have failed this season im sure. Just another thing ruled out as not the problem. You can here in the video how loud the rear (high pressure) fuel pump is. So noisy, kinda wondering if thats the problem. Don thanks alot for responding on a Sunday, I really appreciate what you do here.

Chad
 

cobalt1999

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

I am looking over the problem and and the diagnostic that was applied, reviewing the "MD" TBI manual...... I am confused as Chad mentoned a low and high pressure fuel pump, the "MD" manual only mentions one fuel pump which operates 9-13 psi.
If the system we are looking at has a low and high pressure pump, shouldn't the high pressure pump be around 30 psi?
Maybe we have the wrong engine identification?
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Hello,

It is a volvo pents 5.7 gi pmda, i am not sure if that manual is the correct one, i noticed the same thing that you did. I spent a lot of time reviewing that manual yesterday. I also read somewhere else that the pressure should be a lot higher on high side though im not sure if they were reffering to the right engine. They also refer to the low pressure pump as a lift pump, the lift pump line goes into a fuel box on backside of engine, and the one steel line goes to the tbi unit out of the fuel box. the second line comes out of the second pump (high pressure pump mounted on fuel box) and into the TBI unit.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

In the video the lift pump or low pressure, is just to the left of the heat exchanger, above the fuel filter. The second pump is in the back of the engine, right behid the flame arrestor on its side.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Hello,

I was searching my problem and found someone else who had similiar problem and it ended up being clogged screens in the lines that go to the VST tank ( assuming this is what its called, i was reffering to it as fuel box). I did not know about these screens but a couple of people said they had the same problem. Im assuming if i unscrew the lines going to this box i will find the screens they are talking about. I am going to check it out today, hopefully if there are O-rings I can salvage them.

Chad
 

Tail_Gunner

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

1. The old motor had two oil preasure sensors or switches. One towards back of intake mani. and one in side of block right above the oil filter. When i was switching over parts the one on the side broke and I was having a hard time finding an identical replacemetn. I started the motor with one of the sensors (one on back of intake) and the guage works, good oil preasure, but it bounces sometimes. I read somewhere that not have the second oil preasure switch can cause issues.



That sensor above the the oil filter is a knock sensor..It can sense knocks and retard the timing if they are present...I believe if you open you will see water come out..that would confirm its a knock sensor.
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

Hello,

Thank you for the feedback. This engine only has one knock installed and it is near the starter, you are right about the second knock location but this one was never installed before changing the motor. Near the second knock sensor port is also an oil port for the second oil switch which was installed. I have actually installed the second oil sensor at this time though it didnt make a difference.

All of my research shows that this engine only has one (1) knock sensor.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

I am having it scanned probably today after work for 100 bucks, seems like good deal. Hopefully this will eliminate a lot of other things.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

OK so went to marina today, asked how long scan would take, they said 5 min 100 bucks, i said lets do it, and they said maybe sometime this week leave the key.

Im like but it only takes 5 minutes and they ignored me.... I told them to call when they have extra 5 minutes. Not sure what the problem is but the boat is in a slip there and i have paid them a ton of money for parts and the slip......

So the reason im posting this is...if anyone has any idea of how to proceed let me know, not sure when marina will have time to scan it.

Im probably going to try and locate these fuel line screens that i have heard about around the VST box.

Chad
 

cc190cc

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Re: 1994 Volvo Penta 5.7GI - major power surge problem - possibly timing - possibly f

FIXED IT !!!!!

The inlet screen on the high pressure pump was completely clogged. I cleaned everything out well and now the pump is completely silent. Got 5 or 6 good revs out of it and the pump got noisy again and problem came back. Before i could only get 1 rev before problem. The VST/Fuel box must be full of ****, i am going to clean it out really well tomorow and finally go fishing.

I will post a video of the boat in action. Don and everyone else, thank you very much for all of your help. I hear a lot of people complaining about similiar issues and noisy pumps, hopefully this helps some people out...10 hours later.

I really am glad i did not pay the ****ty marina a dollar to scan this thing.

Don, again thank you very much, im sure this wont be the last time :)...video tomorow if you care.

Chad
 
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