Can I get some help with this intermittant Holley problem please?

[aggressive male]

Hi,

I have a Holley pro-jection fuel only 2 barrel system. Been working great for at least a year but lately sometimes when I turn on the ignition key you won't hear the fuel pump and the fuel pressure guage will show it didn't pump up but if you open the throttle you can hear the injectors buzz even though they're not squirting anything. I can shut off the ignition and come back hours later sometimes and the car will run fine. I get the feeling it wouldn't be loose wires to the pump because it has never stopped running on bumpy roads or anywhere while driving. Only after it has been sitting a while. Anyone got any idea's? Thanks

[aggressive male]

Oh yeah, maybe it would help if I mentioned I'm not using a relay for the fuel pump, I just wired the pump directly to the computer, I only set the fuel pressure at 15 psi though so not a huge load. Is the ecm supposed to be able to handle this? Could it be I burned out the electronics in the ecm bad enough that it only sometimes works? Or is that impossible? Been running like that fine at least a year.

[69Bbird]

I would see if the wire is getting power when you turn the key. If so see what your amp draw is? Holley says to use a relay over 10amps.

[aggressive male]

I would see if the wire is getting power when you turn the key. If so see what your amp draw is? Holley says to use a relay over 10amps.Thanks 69Bbird. How do I figure out what my amp draw is? I'm using the regular holley pump at 15 psi, Could this be too much? Or maybe could they draw more amperage as they get old?

[tom1]

amps = voltage divided by resistance, and most cheap multimeters will give you voltage and resistance

[MonzaRacer]

NEVER, NEVER, NEVER run a high amperage unit like a fuel pump from a computer.
The fuel pump driver circuit is probably shot and its a wonder you havent been stranded yet.
AND I would bet the brushes and armature inside look like crap too as the computers USUALLY ground the fuel pump circuit and depeend on the chassis ground through the computer to complete the circuit.
You may have gotten lucky and the computers ok but the pumps fried.
Get a good 30 amp relay and wire it in, run 8 to 10 guage wire to the pump and have the computer run the relay, also you need to wire in an oil pressure switch in to start the pump after a few cranks and you get oil pressure and it kills it if you wreck and the engine dies.If not it makes a bad fire hazzard.
My favorite relays are the oval units from GM, the square ones can handle 30 amps but the oval ones can take a 70 amp surge an dI had a fella even using one as a starter relay!
Good luck and hope you didnt burn out the computer, if it hasnt got any warranty you might be able to get the fuel pump driver chip replaced locally.
Lee Abel
AFTERMARKET PERFORMANCE

[aggressive male]

Thanks Monzaracer! Lucky I only stranded myself at home. I guess if I did damage the fuel pump circuitry I'll have to wire it to an oil pressure switch or something else until I get a better computer.

[DeltaT]

If it's still buzzing the fuel pump it is probably enough of a signal to trigger a relay. Set one up - very easy - and wire the hot side to the battery and a good ground and try that. You said it works sometimes so don't give up on that circuit yet!

Jim

[andy2175m4]

I agree with the other posters that the ECU should not carry the full current for driving the pump. Although Holley says 10 amps thru the ECU is ok, it's much safer to drive a relay with the ECU and drive the pump with the relay.

Re. the intermittant fuel pump, the wire connectors on the pump are probably corroded and the wiring should be checked and replaced.

My Holley fuel pump is exposed and the wiring and the push-on blade connectors will corrode over time. The bosch-injector type connector on the Holley pump can also corrode over time. While you're installing the 30 amp relay, you might want to also replace all wiring and connectors from ECU to pump.

[aggressive male]

Thanks guys!

[MonzaRacer]

Yuo can also check out www.diyautotune.com and look at Megasquirt.com you could run the tbi with megasquirt and even its upgradeable and much easier and better to tune in.
and no Holley people to deal with.
and great forums to help you out.
AND the computer can be built by you or a local electronics guy or bought done and you can even have it repaired locally too.
also the Microsquirt is even more compact too.