7.4L 1996 Mercruiser Electric fuel pump issue

[smithrockne]

When my 1996 Sea Ray with 7.4 L Mercruiser engine gets warm (+165 F) and is shut off and sits for awhile (30+ minutes) and/or after idling for extended time (+30 min), it won't start/run. I installed a fuel pressure gauge after mechanical fuel pump and on high pressure side after electric fuel pump. When this stalling condition occurs, the low pressure side stays at 7-8# and high pressure gauge goes to zero. The only way I have been able to restart it is to open the hatch and let it cool down to 145 F. Then it starts and runs fine. Engine serial no. is 0F 802308. Engine has approx. 1200 hours. Any suggestions?

 

[Fun Times]

Possibly a vapor lock issue in the fuel VST tank.

Sometimes either getting more cool air to the engine area may help some but not always…but more often of a repair would be to reroute the fuel return line away from the fuel filter adapter and back to the fuel tank somehow safely.

VAPOR SEPARATOR TANK

VAPOR SEPARATOR TANK

www.mercruiserparts.com

7.4LX BRAVO (MPI)(GEN. VI) GM 454 V-8 1996-1997 - 0F802000 THRU 0K999999

7.4LX BRAVO (MPI)(GEN. VI) GM 454 V-8 1996-1997 - 0F802000 THRU 0K999999

www.mercruiserparts.com

 

[alldodge]

Welcome
Agree it's vapor lock

Takes some doing to fix the issue but you could get going sooner if your careful.

Have on hand safety glasses, rags, small flat blade screw driver and ziplock bag or other kind of container.

With safety glasses on, remove the schrader valve cap (item 14). Place screw driver next to tip on schrader valve and rag around the valve. Press in on the valve and have someelse turn key to ON, then back off.

If you see fuel get the rag wet, clean the gas up and remove screw driver and try to start. If it starts place rag in ziplock bag.

https://www.mercruiserparts.com/bam/subassembly/31924/2342/10

 

[tpenfield]

I agree . . . the VST pump probably needs some maintenance (cleaning, etc). A similar thing happened to my 1996 7.4L engines shortly after I sold the boat, as reported to me by the new owner. About 1,100 hours on the engines.