Volvo 5.7 gxi c No Start

[carm64]

Greetings.....my Cobalt 240 just stopped about 3 weeks ago and needed to be towed back to the house. I have been spending the weekends troubleshooting. Good fuel. 52 psi on the rail. Good spark on the coil (new) as well as at all 8 wires, new plugs (trying everything). I did a compression test. Seven were about 200, one cylinder was at 160 psi. The low one I figure could be attributed to perhaps a dirty valve as I had noticed a smaller gap on that plug when I took it out. I checked the injectors for pulse....which all were good, I questioned the strength of the spark so replaced the coil. I also jumpered the test connection which revealed no fault code. The only number that blinked was 12 12 12 12. I am going nuts trying to figure this out. Serial number on engine: 4012063388.

 

[alldodge]

Those are some high compression numbers, new motor are around 150. Where any of the plugs wet as in water found? Could just be the gauge

Have spark and have fuel pressure. Will it run if a very small amount of gas is dribbled in the throttle body?

 

[carm64]

alldodge,
I forget to mention that I was going about 45 mph and the boat had a couple of instances of hesitation then recovery before finally just stopping.

>...this was the first time ever taking compression readings on an engine and I kept cranking on each cylinder until it the pressure stopped climbing. May have been a defective gauge or operator error. My dad said the same thing regarding the pressures. I was trying to rule out head gasket and timing chain issues.

The plugs were wet when I pulled them out, but smelled like fuel. I did not find water

The engine did fire one time (3 weeks ago combust after putting a couple ounces into the throttle) BUT it has not occurred since then. Even after changing the plugs on Sunday, it does not run if dribbling gas down the throttle body.

I was told by the marina/repair shop it would take 3 weeks to get in so spent time checking things out. I have spark and fuel pressure. The engine does not run. From what I have seen there should be 4-8 psi pressure on the low pressure fuel pump and about 50 psi on the high side. I originally saw 46 psi on the high and nothing really on the low side. So I panicked and replaced the fuel pump (looking back it was probably NOT my problem). BTW I still see no pressure on the low side....but my high side is at 52 psi. I also disconnected the test gauge off of the high side Schrader valve and pumped gas into a mason jar, it flowed freely (gas on the fuel rail). I then used the gas in an old push mower....which started right up (good gas, not old and always use STABIL). The spark looked good originally, but questioned the intensity, even after using a spark measuring tool. So I replaced the coil.....dumb mistake. After checking all of the resistance measurements on the old a new coil, they were very similar. More money not wisely spent. In desperation I also ordered a MAP sensor and replaced it. In the repair manual I saw that that sensor could also prevent the engine from starting. Confused as hell in Alabama.

Thanks for your response!
Carmine
USN Retired

 

[alldodge]

Gas mixing with water will smell like gas. Remove all the plugs and note if any still look wet. Gas should evaporate but water won't. With plugs out spin the motor over to see if anything comes out of the plug holes.

 

[carm64]

Gas mixing with water will smell like gas. Remove all the plugs and note if any still look wet. Gas should evaporate but water won't. With plugs out spin the motor over to see if anything comes out of the plug holes.

I won't be able to get to it for a few days, I am at work 80 miles away.....if there is water........what does that indicate as my issue???? Head gasket? Block?

 

[alldodge]

Yes, head gasket, head, block or exhaust manifolds
When it died, hope it died gasping or sort of slow and not a rock hard stop. The thing that's puzzling is you have spark and gas down the TB won't even hit once. Not hitting if water is in the cylinder then that can help explain it.

A lawn mower will burn stuff that a motor would have a hard time doing. That said it should still hit if a spark come close

 

[carm64]

Yes, head gasket, head, block or exhaust manifolds
When it died, hope it died gasping or sort of slow and not a rock hard stop. The thing that's puzzling is you have spark and gas down the TB won't even hit once. Not hitting if water is in the cylinder then that can help explain it.

A lawn mower will burn stuff that a motor would have a hard time doing. That said it should still hit if a spark come close

it did not gasp.....hard stop. But there are 8 cylinders.....if there is water in one......I would think that one of the others would have at least ignited

 

[carm64]

I guess that I could drain the water from the clock and exhaust manifolds and let it sit a bit. Then with the boat on a lift just crank it to see if it starts, not let it run...just to see if I get combustion.

 

[carm64]

I guess that I could drain the water from the clock and exhaust manifolds and let it sit a bit. Then with the boat on a lift just crank it to see if it starts, not let it run...just to see if I get combustion.

Also if I had water in my cylinders/block.....wouldn't that be indicated on my dipstick with a change in level/color(white)? Just asking...thank you for your help.

 

[alldodge]

A hard stop like turning the key off, or a hard stop with a clunk. A clunk would mean water in a cylinder or two and might have damage to rods.

Don't bother with draining water, I just would like to know IF there is any water in the cylinders.

 

[carm64]

alldodge,
No clunk.....just dead stop. I do have one of those camera scopes that I can stick on the spark plug hole also......perhaps I will be able to see what's up in there. On numerous occasions over the last few weeks I had all of the plugs out and cranked the engine, with the fuel relay pulled, just to vent the cylinders. I never thought to look at the holes for water to come out. I should have joined this post 3 weeks ago.

 

[alldodge]

ok

 

[carm64]

ok

There is no water that I can see in the cylinders.....all the obvious stuff seems in check. Since I am getting 52 psi on the fuel rail that should mean fuel out of the tank is good. Good spark on coild and all wires, using a spark measurer. I have had this boat for a year. When I checked the gap on the plugs after the boat failhed, they were set ay .045, the manaul calls for .060. The plugs were not looking too bad. I just figured for the cost just change the plugs and gap them to .060. Good signals on the on injectors using a light probe and NOID lights. Is it possible that I might have ran out of gas....or got so low that I caused some sort of damage. When I got back to my dock I went and got 15 gal ethonal-free in gas cans and tdumped the gas into the tank. As metioned previously, even poured a little down the throttle body....no luck. I have a million things going through my mind as possible faults. I hate to get it taken to a marina...and them find something so simple as the fault. Anything else that jumps out?? Thanks for your responses.

 

[alldodge]

Good spark, good gas and it doesn't fire, doesn't make since. Gas down the TB and good spark would make a back fire if nothing else. Something that appears to be happening is not.

Just doesn't add up

 

[carm64]

Good spark, good gas and it doesn't fire, doesn't make since. Gas down the TB and good spark would make a back fire if nothing else. Something that appears to be happening is not.

Just doesn't add up

Yes....great spark, good fuel pressure at rail. Thought about injectors.....geting both good signal and voltage. Even if they were bad< I should/ hear something when pouring fuel down the trhottle body.....perhaps I am not pouring enough in???? Perhaps the gas that I bought was not good enough for the boat motor???? Still don't understand what would cause it to just quit???? Could it stopping abruptly damage the timing chain causing something to be out of whack? I know it has electronic timing. I did have compression on all cylinder, actual readings are questionable.

 

[carm64]

alldodge.....I ended up getting towed to a marina. I got a call saying the distributor was cracked. The replaced that and checked my plug gaps and it started. How was I getting a spark on the wires? Also they said it keeps pumping too much fuel in and flooding the engine. Could this be caused by the new fuel pump that I installed? Or could this be a defective fuel pressure regulator?

 

[alldodge]

Those motors use what we call a crap cap. They are flat and fail without warning and can look great. Most keep a spare on board just in case.

Measure your fuel pressure should be 50 to 60 psi at the fuel rail.

In most cases if the injectors are dumping fuel then the injectors have the issue. Might be bad or could be dirty and are stuck open by a small piece of crud.

The fuel is coming from the injectors or someplace else?

 

[carm64]

He said he had 62 psi on the rail this morning. Could that cause too much fuel to get pushed into the cylinders?

 

[carm64]

Should I go give them the old fuel pump to put back in......it was showing 48-50 psi the times I checked it,

 

[alldodge]

Should I go give them the old fuel pump to put back in......it was showing 48-50 psi the times I checked it,

No, your fuel pressure is fine
If the injectors are leaking then they are the problem. I would suggest pulling the injectors and have them cleaned and flow tested. Don't use a place that mainly does autos, it needs to do marine.

Mercruiserparts.com
or
boatsunlimited.com

There are some others