1997 Merc 5.7 Stalling after 15 Seconds

[Insanegtp]

End of last year we got water in engine, didn't know tried to start and cracked flywheel, removed all plugs drained water, filled with oil, did like 5 oil changes. REplaced flywheel, did comp check, all between 155 and 160.. re-installed engine last night, started first shot, but runs for 15 seconds... ?!? everytime starts mint, 15 seconds later it's like someone shut the key off... any ideas? oh yeah, we did coil plugs wires filters, all the standard stuff.. thnks in advance -Keith

 

[Haut Medoc]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

My guess is that it is the oil pressure safety switch that kills the fuel pump when the key is in the 'run' position if it is defective....
The pump works in the 'start' position because of a different voltage path....
What I'm trying to say is that you are running out of gas evry 15 seconds until you put the key in the 'start' position....
It is not a big problem....
Let me see if I can find a pic....

Here ya go.....
Temporarily by pass the switch to see if it will run continuously....
DO NOT use this as a fix, other than in an emergency.....
Pic courtesy of Don S....

 

[Insanegtp]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

Thanks for the reply, and pardon my ignorance, but how do I bypass this.... ??

 

[cooter2506]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

JUst jumper the two wires together, for testing only dont leave it that way replace switch if bad. Switch is cheaper than replacing engine if you loose oil pressure and dont know it.

 

[Don S]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

Thanks for the reply, and pardon my ignorance, but how do I bypass this.... ??

Locate the oil switch just above the block mounted oil filter. There are 2 wire connections on it. A piece of wire with an alligator clip on each end attached to the leads on the switch should do the job.

 

[Insanegtp]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

Still no go, the only switch I can find on near or around the filter has only one wire, I used a power probe and the fuel pump does not shut off the duration of it runing.. any other ideas??

 

[BDM Boating]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

Did you check the idol in the carborator? It might be light.

 

[Insanegtp]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

Idol ? Not sure I have ever even heard of that.. sorry... I am famaliar with car engines and a few boat motors, I just am really stumped on this.. Spark stays good right till the last sputter.. coil not hot, fuel pump going, throttle body injectors were WERE pusing, a few minutes ago before I had to come in and help some customers there was no fuel coming from t/b during crank, this is a first cuz up till now it would start EVERY time... either something else just broke, or the problem is becoming more apparent....

 

[Maclin]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

I think most previous replies were from a carbed engine point of view.

A throttle body fuel injection unit has a couple of circuits and supporting sensors or modules that need to be addressed. One is the Idle Air Circuit (IAC), the other is Throttle Position sensor (TPS). Some use a Mass Air Flow sensor (MAF). I am not sure on yours, but usally the IAC is suspect with the symptoms you describe.

 

[coastalcruiser]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

runs for 15 seconds... ?!? everytime starts mint, 15 seconds later it's like someone shut the key off...

Just throwing this out there, the fuel pump has a safety shutdown , is there anyway that could be the problem?
just a thought...

 

[Insanegtp]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

I beleived fuel as well, but the pump does not lose power nor ground... I just tried again, ran for like 3 or 4 minutes like champ.. then outta no where sounded like key turned off... check the big *** plug, reapplyed dielectric put back on, tried starting again and nothing, no start, looks like t/b is spraying to LITTLE fuel....

 

[Insanegtp]

Re: 1997 Merc 5.7 Stalling after 15 Seconds

Think I got it.... was just really poor gas, dumped filter half water half gas... dumped again, sametthing check last time, was pretty clean, has been running gfor almost an hour... thanks guy and gals...