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Mercruiser 74L MPI No Fuel Pressure

T

timmber

New member
After my engines warm up the f

After my engines warm up the fuel pressure drops off and they die. Have tried almost everything.
 
Whats your oil pressure look l

Whats your oil pressure look like during this
drop off? What Has already been done? Check
oil pressure fuel pump switch.

Kurt
 
"Well, there is no oil pressur

"Well, there is no oil pressure switch on a EFI/MPI engine, so it's not that. Are both engines drawing from the same tank?"
 
Check your wire diagrams as th

Check your wire diagrams as there should be a oil pressure switch to kill fuel pump in the event of oil pressure loss. All efi engines I have seen incorperate this feature.

kurt
 
"Kurt,
Don't want to star

"Kurt,
Don't want to start an argument, but the primary function of the oil pressure switch is to determine engine state (run/stall), for fuel safety, not engine self preservation. This applies to carbed engines equipped with electric fuel pumps. An EFI engine uses an ignition reference signal to determine engine state."
 
"From what I see on merc wirin

"From what I see on merc wiring diagram, the oil pressure switch is bypassed when the key is in the START position so that the pump WILL run without oil pressure. Otherwise the engine would not start as there would be no fuel supply.
Once the engine is running, then the fuel pump will get power only as long as there is positive oil pressure. If oil pressure is lost, fuel flow stops. for efi I see they incoperate a 2 second pump run for start up, commanded by ecm.

Kurt"
 
"Anyhoot,
seeing both die, I

"Anyhoot,
seeing both die, I would check tank vent for clog or low spot holding fuel. try running with fuel cap off and see if this helps. Also check
anti syphon valve. may also consider both pumps inlet screens for debri.

Kurt"
 
"Update to all,
turns out the

"Update to all,
turns out the gas was bad, never had that happen before. Pumped all of it out (alot) refilled with fresh gas all is fine."
 
"Glad to see someone mention b

"Glad to see someone mention bad gas. Here in WNY, we have been having terrible problems with ethanol blended fuel. Besides being a scam, it is absolute crap fuel and is wreaking havoc with all types of cars, chainsaws, mowers, boats etc. I have personally talked to the local refinery and found one that does not add it (yet) to their fuel. ALL of my driveability problems went away as soon as I started using their gas, and have been sending evrybody to them since."
 
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