Hi all -

I have a very reliable 94 250 w/318 MPI that out of the blue will not start.
Has spark, timing is fine, alll the usual trouble spots have been fixed, plugs, cap, wires all good; I suspect a low fuel pressure problem. Pressure at test port on rail is (only?) 40 PSI. I understand the spec is 49 psi +/- 5.

Is this pressure sufficiently low to prevent the injectors from firing? If so, what is the likely culprit - pump, regulator, split hose in the fuel tank? (been there on the last one). Please advise.

Thanks, John D

 

Will it start if you crack the throttle a bit while cranking?

Welcome to DF.

 

Hey, Hey You -

Thanks for the welcome. Yeah, we tried everything w/ the throttle plate position. No good.

Strong spark at plugs and coil ....

Hmm, just thought of something. Starting fluid had no effect - that kinda shoots a hole in the low fuel pressure notion?

Ideas anyone?

 

Pull a plug or two, and have a look at them. See if they are fuel soaked, or fouled in some other fashion. If you are getting spark, hitting it with starting fluid SHOULD get some action........

 

HY -

Had already pulled four of them - all soaked with fuel. Malfunctioning plugs was the only thing that made any sense after it registered with me that the starting fluid did nothing. Compression + spark + flammable substance usually = bang, or at least pop. On my way to NAPA now for 8 x RC12YC. I'll let you know how it does with fresh plugs.

Thanks, John D

 

She's running fine now. Likely cause of problem: distributor cap had lots of powdery junk inside it that might have been causing severe tracking that caused a misfire/no fire condition, causing the plugs to get soaked. After the cap was cleaned up (including the rotor and contacts) damage to plugs had already been done. Fresh plugs, fired right up, runs great.

Thanks all for your help.