Volvo 5.7 MPI Gi-E starting issue - solved

It is either lack of compression, fuel, or spark. Compression pretty much ruled out as it runs well once it starts. My guess is it's electrical as it is intermittent.
 
Thanks Greg. Appreciate the feedback. The fuel pressure checked out fine. Low Pressure was 12 psi and the high pressure pump was at 50psi, both right on spec. removed the fuel pressure regulator , inspected it - a very little amount of debris/dust on the screen. I cleaned it up with carb cleaner and reinstalled. No issues with the oil either.

Remember - I was running the boat for a while with a very dirty flame arrestor - so it was not getting the proper air flow for a while. What other problems would this cause?

1. Would dirty fuel injectors cause my starting problem but not affect the engine once it is running?
2. I'm also thinking it could be the anti-siphon valve not working properly, however, I don't think I would get the good performance once the engine is running that I am getting if this valve wasn't working properly. I would love to change it but there is some type of sealant on the threads and I can't seem to unscrew it. The location of the anti-siphon valve makes it difficult to get any leverage on the nut.

I'm pretty convinced it's a fuel issue at start-up. That's all for now. Thanks for any continued suggestions.
 
1.) yes.

Have you tried the FULL WOT throttle lever setting during an attempt to cold-start yet? Since that setting de-activates the MPI injectors, it's a test to see if injectors are fouled and leaking with engine off to create flooded condition. Just be ready to reduce throttle right away if it gets enough air and fires up.

2.) possible .

Since you reported plugs were wet , they were clearly getting liquid and presumably too much fuel ( hopefully still good quality.)

Does that Merc MPI engine use a distributor , ...and have a spec for Cam Retard Angle ?
 
If it is an MPI, it should start with the turn of a key. The computer should adjust all parameters to get it started. Do a complete engine condition check (check all electrical starting at the battery), check your grounds, then check to see if the engine is throwing any codes. The best is to run it with a Diacom software laptop attached, especially when it is acting up.
 
Thanks for the feedback.
Sandy - its a Volvo and I think the plugs were wet because i was trying everything to start it at the time and probably flooded it.The injectors are next on y list but may need professional help with that one. I've gotten pretty far myself with the help of others and good old youtube!

GB - thanks, I don't have that equipment but it may be time to have a mechanic look at it and see if there are any codes.

Thanks again all
 
Are you sure there's spark when it's cranking but won't start? Knowing that will eliminate 1/3 of the possible problems.
 
What I'd check:
1. verify spark at spark plug with a spark tester (safer)
2. remove all plugs, disable ignition, and crank engine over to check for water in the cyls. your symptoms could be suggestive of this, esp wet plugs, esp if the center insulator is an orange color...
3. check fuel pressure at fuel rail

4. If #1 and #3 check out but you have water in the cyls then you have to figure out where its coming from...manifold/riser, or head gasket/head...also do a compression test.

5. If you are in brackish water keep in mind that the risers and manifolds should be changed every 5/7 years on raw water cooled engines or else you can get water leaking in at the joint between the riser and manifold, or the riser or manifold themselves can rust through and put water into an exhaust port.
 
quote:
Originally posted by bobh

Thanks for the feedback.
Sandy - its a Volvo and I think the plugs were wet because i was trying everything to start it at the time and probably flooded it.The injectors are next on y list but may need professional help with that one. I've gotten pretty far myself with the help of others and good old youtube!

GB - thanks, I don't have that equipmet but it may be time to have a mechanic look at it and see if there are any codes.

Thanks again all

Click to expand...


Sorry, my mistake about "Merc"- you did say it was a Volvo right off.

That engine will have a Cam Retard Angle specification to ensure the dist. rotor is properly close enough to each cylinder's dist. cap electrode when the ignition pulse comes from the coil.

Setting Cam Retard requires using a marine scan device ( not a code simple reader) to display that parameter , which is adjusted by revolving the dist. base, then re-securing it's clamp. Must be within +/- 2* of the spec. .

(Same idea as adjusting timing on non-MPI engines... but in this case timing is unaffected since all timing including initial is completely controlled by the ECM.)

If you get access to a scan device , it is also then easy to perform a Power Balance Test when the engine is running by clicking that command on the scanner.
That sequentially de-energizes either one injector or one sp. plug at a time while you watch for any de-activated cylinder which does NOT reduce rpm, to show it was not combusting normally.
 
Starting problem solved --coil!!

Unfortunately I didn't have access to the Diacom software so had to work through a lot of potential issues. Thanks for all of your help and suggestions. A couple of people mentioned spark as a potential cause. I found a post on another message board that was very similar to my issue and eventually it led them to figuring out it was a bad coil. Once I replaced the coil it fired right up.

I think I was dealing with multiple issues with my boat. The dirty flame arrestor was inhibiting the proper air flow in the engine. Again I'm far from an expert...not sure if coils go all at once or if the spark deteriorates over time.

Glad I finally was able to figure it out. I had put a work order in with the marina but was told that I would have to wait three weeks because they were pulling boats. That's when I decide to check the coil.
 
You must log in or register to reply here.
Back
Top