Volvo Penta 7.4L will not stay running

[Green Cobalt]

Hello all. . .i used to have an account but i have not been on in so long i created a new one today. . . I look forward to constructive critism Go for it Bondo

1996 Cobalt 220 with a 7.4L Volvo Penta with Duoprop

My dilema is this. . . I have owned the boat for 2 seasons now and its mint! Never had any problems. Then Sunday we went to the lake and put in like normal. It started up then died. After that I could not get it to run again. So i pulled it out of the water and headed home after an hour of messing around with it.

Checked for spark at the coil, at the plugs and at the cap. All was good. .

Checked for fuel. It is getting fuel durring crank. . .

Batteries are new and fresh. . .

Decided that i would replace plugs and get a new coil while i was at it. .

Got that done this morning and it fired right up. It ran for about 10 seconds and died. . AND NOW IT WILL NOT START AGAIN?????????????

Am i missing something so small and stupid???????

Any help would be greatly appreciated
Erik

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

Can you say fuel pump relay?????
What is the FULL model number of your engine and I can be a lot more specific. Something like 7.4GL XXXXX Need the letters where the X's are.

Volvo Engine ID

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

Sorry i guess i left out a few details. .

the only tag i can read or see on the engine is 7.4GL PNCA with a string of numbers that are not very readable after that.

Also the engine is caurburated.

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

Great.
That long number is the serial number, but you have an NC model, that is what I needed to determine.
Be back in a bit with how to check it.

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

Thank you sir

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

The first thing you need to do is locate the fuel pump relay. It should be right next to the fuel pump itself.
Pull the relay out of the socket.
Next, with a meter, check that you have battery voltage at terminal 30 on the socket. It should be hot any time the battery switch is on.
With a jumper wire, jump between 30 and 87, you should hear the pump run. If you do, then you know the pump is ok.
Pull the wire back out.
Now check terminal 85. This will require you crank the engine, so pull the coil wire out of the distributor cap and ground it.
Crank the engine over and verify voltage on the 85 terminal.
You you show voltage there, that means you are getting power to the relay.
Now, do a continuity test on the 86 wire (GROUND) If it's ok,
Then replace the relay and see if it will start.
A quick check to make sure the engine runs is to make a jumper wire and go between 30 and 87 and see if it will start and run.
If it does, also check terminal 85 again with the engine running to make sure you have power to the 85 terminal. While running, it gets power from the alternator thru a diode.

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

Don,

I went through those steps and all checked out and i even replaced the relay but still having the same result?

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

When it won't start, does it have spark?

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

yes, there is spark when i ground out the lead from the coil and if i pull a plug and check there. .

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

Did you try running it with the relay removed and a jumper wire between 30 and 87 ?

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

After it dies, and won't restart, did you pump the throttle and check to see that fuel would squirt from the accelerator pump holes into the engine?

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

yes i did that too and it still didnt start. . Now when i jump the wire to turn on the pump it starts out loud and then it slows way down. . is that how it should sound? Also I did spray starting fluid in the carb and it did crank over that way til the fluid burned off

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

Disconnect the throttle linkage, put in the jumper and pump the throttle and see if you are getting gas from the accelrator pump holes while the pump is running.

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

I disconected linkage and hooked up the jumper. . i could pump fuel into chanber by hand but that pump doesnt seem to push anything through now that i am back there looking at it. . and it starts fast but slows way down over about 6 seconds. I am guessing from whats left that i have either a bad pump or something maybe clogging the line??????Boy do i love boats lol

 

[Coors]

Re: Volvo Penta 7.4L will not stay running

Or it build up pressure after 6 seconds?

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

It shouldn't slow WAY down. Disconnect the fuel line at the carb. Put a hose over the end and run the other end of the hose into a container and jump the relay and see if the pump puts out any fuel. You really should do a fuel pump pressure test if you have a gauge. You should get 5 to 8 psi.
You might also check the filter in the carb.

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

I dont have a pressure gauge. . but i did disconect and ran it into a pop bottle. . plenty of fuel making it to the carb. . should i try a rebuild kit? I would guess that it has never been done on this carb. Or is it something on a totally different track?? I am dumbfounded.

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

Did you check the fuel filter in the carb where the line goes in?
When you did the starting fluid thing (man I hate that stuff) was the relay bypassed?

 

[Green Cobalt]

Re: Volvo Penta 7.4L will not stay running

yes i checked the filter. . it was fine. I had the relay in and out when i sprayed some starting fluid in.

 

[Don S]

Re: Volvo Penta 7.4L will not stay running

What I was trying to determine is how it works without the accelerator pump.
Try this.
Pour some gas (not starting fluid) into the carb. Put the jumper across 30 & 87 in place of the relay, then start it and see if it will keep running. You may have to keep the rpms up because the accelerator pump may not work.
If it doesn't, it's carb problems.
If it does, it may be accelerator pump only problem.