Mercruiser 7.4 MPI 1998 stalls when cold start

[Micke9000]

Hi.

I have a Merc 7,4 MPI 1998 and my engine stalls everytime i do a cold start. It runs about 2-5 sec and then it?s just shut off. Stalls. But if i give throttle in the start i can sometimes get the engine to run, but if i back off the throttle the engine stalls.

If i let the engine start and stall one time, it starts and runs fine the second attempt

I have cleaned the IAC valve and change the fule filter with no effect.

Compression is fine.

Could it be the IAC anyway?

Oil pressure swith?

Anti-Siphon valve?

Kind regards
Micke

 

[Scott Danforth]

Re: Mercruiser 7.4 MPI 1998 stalls when cold start

most boats are temperamental when starting cold.

 

[alldodge]

Re: Mercruiser 7.4 MPI 1998 stalls when cold start

Hi.

I have a Merc 7,4 MPI 1998 and my engine stalls everytime i do a cold start. It runs about 2-5 sec and then it?s just shut off. Stalls. But if i give throttle in the start i can sometimes get the engine to run, but if i back off the throttle the engine stalls.

If i let the engine start and stall one time, it starts and runs fine the second attempt

I have cleaned the IAC valve and change the fule filter with no effect.

Compression is fine.

Could it be the IAC anyway?

Oil pressure swith?

Anti-Siphon valve?

Kind regards
Micke

:welcome: to iboats Mickie

It could be the IAC but since if it dies once then it's fine is a puzzler.

Suggest checking the fuel pressure at the shrader valve on the fuel rail. Also check to see if your vacuum line is connected from the intake to the pressure regulator (Item 15).

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=809994 98&ivar=images/COMMON/20147.png&inbr=2705&bnbr=110&bdesc=FUEL+PUMP+AND+FUEL+COOLER

Also, there are 2 relays on the engine, one is the main power relay and the other is for the fuel pump. Both relays are the same, swap them and see if anything changes (Item 27).

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=809994 98&ivar=images/COMMON/35598.png&inbr=2705&bnbr=70&bdesc=ELECTRICAL+BRACKET+AND+COMPONENTS

 

[dubs283]

Re: Mercruiser 7.4 MPI 1998 stalls when cold start

when was the last FULL tune-up??

 

[Mischief Managed]

Re: Mercruiser 7.4 MPI 1998 stalls when cold start

M7 2000 7.4 MPI does that now and then too. No idea why. It runs perfectly otherwise. Seems more likely to do it after sitting for more than a week though.

 

[Micke9000]

Re: Mercruiser 7.4 MPI 1998 stalls when cold start

:welcome: to iboats Mickie

It could be the IAC but since if it dies once then it's fine is a puzzler.

Suggest checking the fuel pressure at the shrader valve on the fuel rail. Also check to see if your vacuum line is connected from the intake to the pressure regulator (Item 15).

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=809994 98&ivar=images/COMMON/20147.png&inbr=2705&bnbr=110&bdesc=FUEL+PUMP+AND+FUEL+COOLER

Also, there are 2 relays on the engine, one is the main power relay and the other is for the fuel pump. Both relays are the same, swap them and see if anything changes (Item 27).

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=809994 98&ivar=images/COMMON/35598.png&inbr=2705&bnbr=70&bdesc=ELECTRICAL+BRACKET+AND+COMPONENTS

Thanks

What gauge and fitting do i need?

Regards
Micke

 

[alldodge]

Re: Mercruiser 7.4 MPI 1998 stalls when cold start

Thanks

What gauge and fitting do i need?

Regards
Micke

Morning, You need a standard fuel pressure tester, one which works on fuel injected cars will work. The fitting is a shrader valve, which is like what you fine on the tires (valve stem)