First off.. I spent a merry (and very useful!) day yesterday reading through all the millions of previous threads on the fuel pump issue. Long story short, my 98 D1 cranks but won't start. It's sat for almost a year (on a trickle charger), but started first time everytime prior to that. It's got 193k on it and has never had any (major) issues aside from the usual leaks.

Fuel pump doesn't come on at startup. No pressure in the fuel rail. I checked the connections at the pump.. +5v on the green (?) wire, nothing on the white/purple. Fuse looks OK, +12.5v at fuse. I jumped the pump, which came on just fine and gave good pressure at the fuel rail.. but she still no starty.

My question is this.. could a bad fuel pump relay still prevent the car from starting, even if there's fuel in the rail? I assume from what I've read that the +5v is a signal from the ECU.. is that correct?

I've got the RAVE CD.. but I can't for the life of me work out which relay is the fuel pump one.. does a '98 D1 even *have* a separate fuel pump relay? I was looking for a blue/aqua coloured relay.. but all the passenger-side footwell relays on mine are yellow or red.

After a bit of poking about with a pressure gauge, I've got 36-38psi at the fuel rail with the pump hard-wired on.. and it drops to zero almost *immediately* when the fuel pump turns off.

Could this be the much-fabled check valve I've read so much about.. or do I need to go get a good crank sensor? Can a bad crank sensor stop the fuel pump from getting power?

Any advice/tips much appreciated!

 

Don't know if this helps, but I had a similar incident last week on my other vehicle (Mazda). Thought is was a fuel pump as it went bad on me three years ago, wound up the timing belt broke. Similar symptoms to my fuel pump. No gas getting in.

Also, any luck using started spray fluid to get it to turn?

 

Yes, it coughs and runs for a couple of seconds if you squirt starting fluid into the intake.. which I guess rules out the crankshaft sensor.

 

The relay is listed in RAVE. look for the procedure on changin the fuel filter, it will tell you to pull the fuel pump relay and gives the location. I can't remember, but I think it is on the left, second one in. I'll see if I can find it again...

 

I'll bet money your fuel pump pressure relief valve is shot.
Next time you cold start it, turn the key to the second position for 5 seconds, this will help prime the syetem, do it 3 times then try and start the engine, what happens?
The fuel pump relay will not cause this and your pump only get 3 or 4 seconds of voltage before the ECU shuts it off, if the engine doesn't start.

 

See.. I think you're right.. I don't really have much else left that it *can* be!

Is the pressure relief valve part of the actual fuel pump unit.. or is it part of the regulator on the fuel rail?

More importantly.. can it be replaced/fixed independently, or (if that's the problem) do I need an entire new pump unit?

 

Part of the fuel pump.

 

Well.. the good news is SHE LIVES..

Thanks to everyone who responded/read this thread.. fault was a break in the wire to the multifunction relay.. I had to take the washer bottle out to get to the relevant bit of the main harness, but it looked like it had been rubbing against a stray bit of wire-wrap for years.

Still a bit paranoid about the fuel pressure though.. I get a healthy 59psi with the pump running, but it drops to almost nothing straightaway.

Now I have to go replace every single vacuum hose I can find.. they're just falling apart in my hands...