Fuel pump wiring question

Technical and Repair Discussions

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PostPosted: Mon Dec 28, 2015 11:59 pm
I had a problem in the last test day, the car would seem to run out of fuel and die, would then restart and run okay and then do it again. Changed the filter etc and it seems to be a wiring issue, losing connection on left handers. Is there a way to put a test light on the fuel pump connection so I can try and find the loose connection? Any suggestions would be appreciated.

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PostPosted: Tue Dec 29, 2015 10:34 am
Is it an intank or external fuel pump?

DaveP

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PostPosted: Tue Dec 29, 2015 8:08 pm
it is the in-tank version.
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PostPosted: Tue Dec 29, 2015 9:04 pm
Have you tested the fuel pressure and flow rate? Assume you have a Gen2 (Gen 3 has FP built-in)?
Bob Breton - SRF 51 - San Francisco Region

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PostPosted: Tue Dec 29, 2015 9:45 pm
Seems to be fuel. Oh boy. First try a fuel pressure gauge on it. If you have one. If not get one. Then do a wire wiggle test with gauge on car running. Tap the relays lightly does it stumble? Power comes from ecu to relay to pump. I think? green at relay fuel,brown main relay. Did you just put the pump in? What was just done to car? With a fuel gauge on car running I would wiggle wires at cell connector and then all other wires even grounds on engine. ALL grab them and jerk and tug on them. If it is a wire problem should find it that way. Only if it is a bad connection or something rubbing and grounding out. You can also make a wire with 2 alligator clips on each end and cut back a little of the wire covering by cell last point of wire one clip on bare wire other on test light. Wiggle dose light go out? If it does then you will have to work your way back to relay. But before I did that I would make sure I was losing fuel pressure. If it is shutting down car due to no fuel pump, but does not refire for a min. you should be able to push schrader valve on fuel rail and get no fuel,also drop off on fuel pressure gauge in shop. Does it fires right back up after a recycle of Ing. switch. Then it come back all by it self? That sounds like relay. Only on left handers? Wire touching or losing connection or relay. May not be fuel. I found more wire and relay problems then fuel pump. The new internal pumps are pretty consistent and I have not heard of a problem yet, but I'm sure someone has. So that is why I'm asking did you just do something to car. Before it was fine I just did? and now it's not. Let me know. Tony Southeast Spec Racer.

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PostPosted: Tue Dec 29, 2015 10:05 pm
Nothing to add to what Tony asked.

DaveP

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PostPosted: Wed Dec 30, 2015 11:01 am
Mine behaved this way in Left handers and bumpy track at the start of the year.
I thought fuel, but ended up electrical

Mine (felt like a miss, and/or car would die completely) and was due to a combination of
1) grime n the big connector near the fuel fill(wd40 clean) after a wet track day
2) a loose blade on the kill switch (2 new switches) and
3) loose green wire on the power connector into the cab (resoldered the whole harness, removing crimps)

I'm asuming you're a Gen2....took me a while to chase all the gremlins
A lot of the members here, including Tony, were very helpful on what to look for..
(thanks again to those helping a brother out)
Fix one thing at a time, and. As tony says, see if you can reproduce the failure.
Scott Cypher
SRF3 #577 G3
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PostPosted: Thu Dec 31, 2015 1:56 pm
If you are running a GEN2, make sure the spark plug wires are not rubbing on any grounded metal, like the cam cover. Check to make certain they are secure and can never rub against, or even come close to, any metal under cornering load.

When that happens, it's usually in left-hand corners, which it appears is the case with your car.

It happened to me with my first GEN2 car about 15 years ago and has happened to a few other guys since. It feels just like fuel starvation, but isn't. Tricky stuff.

Tick this one off your troubleshooting list. It's not uncommon with GEN2.
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PostPosted: Thu Dec 31, 2015 4:07 pm
Bob Devol wrote:If you are running a GEN2, make sure the spark plug wires are not rubbing on any grounded metal, like the cam cover.


Probably the most underrated bit of advice there is...
Dave Harriman
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