Low pressure pump 20psi???

B

BreakOutAnotherThousand

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Volvo Penta 5.7 GSi PEFS

Testing out the system as I'm trying to diagnose a lack of power/misfire/exhaust backfire above 2500 RPMs.
It's not the S.L.O.W. circuit, knock sensor, and oil sensor are disconnected.
CTS resistance checks out on bench test. 10K on ice, 2K body temp etc.
Both injectors spraying fine, cleaned by WitchHunter when pump replaced. SLOW would otherwise kill one injector.

Pressure regulator has no leaks.
MAP sensor, TP Sensor, and MAT sensor all test fine. (yes this engine has one!!) Even though its an MEFI3.
Compression is 190 to 180
Cap, rotor, wire, coil replaced, swapped ignition module.
Timing set.
No codes using Rinda CodeMate.
No water in fuel, fuel cell has 10 hours on it.
Ran with hose in a 5 gallon gas can to eliminate bad pick up.
The only thing I found not to specs is:
HP pump has 39lbs
LP pump has 20lbs!!
Could the LP pump cause the above issue, or is my ECU fried? According to Volvo bulletin, if the ECU is history,
I have to buy an MEFI4 unit for $2,500.00!!!!!!
 
Tail_Gunner

Tail_Gunner

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Messages
6,237
Re: Low pressure pump 20psi???

BrakeOutAnotherThousand said:
Volvo Penta 5.7 Gi PEFS

Testing out the system as I'm trying to diagnose a lack of power/misfire/exhaust backfire above 2500 RPMs.
It's not the S.L.O.W. circuit, knock sensor, and oil sensor are disconnected.
CTS resistance checks out on bench test. 10K on ice, 2K body temp etc.
Both injectors spraying fine, cleaned by WitchHunter when pump replaced. SLOW would otherwise kill one injector.

Pressure regulator has no leaks.
MAP sensor, TP Sensor, and MAT sensor all test fine. (yes this engine has one!!) Even though its an MEFI3.
Compression is 190 to 180
Cap, rotor, wire, coil replaced, swapped ignition module.
Timing set.
No codes using Rinda CodeMate.
No water in fuel, fuel cell has 10 hours on it.
Ran with hose in a 5 gallon gas can to eliminate bad pick up.
The only thing I found not to specs is:
HP pump has 39lbs
LP pump has 20lbs!!
Could the LP pump cause the above issue, or is my ECU fried? According to Volvo bulletin, if the ECU is history,
I have to buy an MEFI4 unit for $2,500.00!!!!!!
Click to expand...

You need the manual...yes high pressure could mess it badly...And no 2500 for a mefi 4....That is insane try 600

http://www.gmperformancemotor.com/parts/88962717.html

Then you just repin your existing harness its very simple. But i do not think your there yet
 
B

BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

GSI, it's Special!! Sorry.

Got the manual. Thats why I emphasized 20lbs. Would that cause the lack of power/misfire/exhaust backfire above 2500 RPMs??

Thanks for the price education!!


Any source for the repin, so if I need a new ECU, I dont have to ask!!

Thanks again
 
Don S

Don S

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62,321
Re: Low pressure pump 20psi???

You have WAY to many things that could be wrong to start thinking you need an ECM. That's where parts changers go, troubleshooters look for the problem and fix it.
If you have 20 psi of fuel pressure on the low pressure pump, fix it. Get the right fuel cell, or get one that works, but that one is obviously not working right. Was it OEM?
You can't fix a low rpm problem with a serious fuel pressure problem. Is that causing the problem, who knows, but you have to fix known problems before you can find the unknown problems.
 
B

BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

You are correct, sir.

I only changed basic ignition which was scruffy at best.
I believe the only issue I have left is the high pressure on the LP pump.

Im pulling the pump now!! It's only 6 months old. VOLVO OEM 21608511. Replaced due to HP pump failing.
Called the seller, and no issues returning it, said Volvo will drop ship me a new one!!
 
Don S

Don S

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Re: Low pressure pump 20psi???

That's a start anyway. You are sure you had everything hooked up correctly didn't you? (Not sure if it could be done wrong, but I can't see it so thought I would ask)
 
Tail_Gunner

Tail_Gunner

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Re: Low pressure pump 20psi???

Assuming its a GSI then its a throttle body and your way to high on both rails. Made short if your pressure gauge is correct your running way to rich. Simple explanation your injectors open and close in terms of milliseconds at a predetermined rate say 19ms at 30 psi...now when you incease the pressure by over 10% you enrich the charge and marine engines run very rich as it is..That could be enough that simple make's your cup more than full.
 
B

BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

I can't now remember if the HP was a typo, was it 39lbs or was it 29lbs??
Too late to recheck.

Yes, Im running rich, the plugs are black but not very sooty, as when a float sunk on my Carter carbs in the 70s!!

BUT!!!!

I removed the fuel cell, while trying to blow out any fuel prior to shipping it back.
Also blowing out any cooling water through the water fittings, I inadvertently blew into the vacuum port, and air/fuel came out of the
fuel fitting.
I popped a MityVac on that fitting (which comes from the throttle body base), and it wont hold any vacuum.
Did I find the problem??
 
Don S

Don S

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Re: Low pressure pump 20psi???

Gee, I wonder if your gauges are correct. Both high and low pumps are 10psi high ?????????????????

Yes, a leaky fuel regulator could be the cause of your problem.
 
B

BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

New gauge, could be bad!?

But my Mityvac doesnt lie!!

Oh being an old school mechanic, I did use a vacuum gauge to see the engine's health, vacuum was 15" and fluttering 2" either way.
There's my vacuum leak, and rich condition.

Don, unlike many on this forum, I will report back with the outcome from a replacement pump.

Thank you for listening, that always helps someone through!!
 
Don S

Don S

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Re: Low pressure pump 20psi???

Check your fuel gauges also, they work on air, just verify them. New doesn't make them right. Been down that road before.
 
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BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

Update:

Volvo wanted the pump sent to them, as it was the latest, new, and improved model!!:facepalm:

They confirmed it was bad, but would not confirm, nor deny my findings of a leaking regulator.

A new one is being shipped to me!!
 
B

BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

Just received the new fuel cell replacement from Volvo Penta.

Still falls on its face, and backfires from exhaust past 2500 RPM.

Fuel pump pressures are 22 PSI low pump, 34 PSI high pump!!!

Any other reason for high pressure in low pressure pump??

Fuel pressure gauge tests fine!!
 
B

BreakOutAnotherThousand

Seaman
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Messages
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Re: Low pressure pump 20psi???

Any one have any idea, why the low pressure pump is 22 PSI??

This replacement, along with the one I sent back to Volvo both.
 
Don S

Don S

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Re: Low pressure pump 20psi???

You don't have any type of electric fuel pump before the fuel cell do you?
 
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