Damn fuel pump wont prime on start up every once in a while. No rhyme or reason, hot, cold, sitting for days or been driving all day it will do it. Replaced the FP relay under the hood same deal. So its either loose wire under the fuse block, a relay/fuse Im missing, or a wiring problem somewhere along the way. Its been so damn long since I put the walbro pump in there I dont remember how its wired up. The pump probably only has 5-6K on it although its about 6 years old

I really dont want to pull the tank so any suggestions? I did a search on the site and couldnt find anything pertaining to my situation.

FWIW I have a fuel pressure gauge ont eh rail and when it wont start there isnt any rail pressure as soon as the fuel pump rpimes and I get rail pressure it fires right off first turn over.

 

Almost sounds like a loose connection... I'd go all over the circuit and wiggle connectors and even look for rubbed spots in the harness... If you've got it running on the stock stuff I'd recommend putting bigger wire to it... A few folks have done pretty nice jobs of doing it on here...

FWIW... I'm going to be running the Denso 300lph pump to have a little extra volume and to avoid the priming issue I always had with my dual walbro setup.

 

replace the fuel pressure regulator.

 

True, on a return system the regulator may be the issue

 

mine loses prime, consistently. Cold starts suck. Regulator is in the tank on returnless systems, no?

 

I would think that but when it doesnt start I can actual hear that the pump is coming on. When I have this problem, I let the window down and cycle the key through the window until I hear the pump kick on then it will fire right off.

Damdest thing is or the first 1000ish miles after I got it up and running I didnt have a problem then all the sudden it started after I got back from my dads(~200 mile trip) last weekend. It did it once fairly soon after I got it up and running but after I messed with the relays under the hood it was fine for a good 800 miles(6 weeks) worth of driving.

 

If pressure bleeds down with KOEO then more than likely it is the FPR.

 

Ill test that and post a video tonight, i know it does bleed down pressure but not very fast. Never really paid that close attention to it. Ive got an extra FPR i can try this weekend.

KOEO= key on engine on?

 

Key on engine off

KOER, key on engine running.

 

Had some time to mess with it today. I started it earlier(~2hours) then went inside. When I came back out to watch and see what is going on with the fuel pressure it still had 40psi in the rail. I cycled the key on and I didnt hear the buzz from teh fuel pump or hear the relays cycle under the hood. The FP didnt move, kept cycling til I heard the pump come on and I had 52 at the rail. Started it up and it jumped to 56-58. So it seems to me the regulator is fine and that its an electrical problem. Just dont know how if its an electrical problem how once it finally energizes(sometimes first try sometimes 20th) it runs fine for as long as I drive it up to 2 hours straight so far.

Ive replaced the FP relay, what should be my next step? I hate electrical problems.