HadaGSL-SE

iTrader: (6)

Hey guys,

I have searched and believe I know what the problem is. See the mods in the sig.

I just put my new motor in and have been having some issues with the car breaking up. Before the last motor blew it would break up occasionally at an autocross event. I figured it was just fuel slosh.

The motor will now break up under load intermittently but often. I also hear a high pitched whine every now and then coming from the rear of the car, even after I turn it off. I believe it is the fuel pump. I was also thinking that it could be that the gas tank or screens on the fuel pump have some debris causing this to happen. I do not believe it to be ignition related. I have checked the fuel injector grounds and made sure that they are on tight (they had come loose before).

Any ideas or suggestions? Ideas on pumps to get? From my reading I understand the 190lph Walbro unit should be pretty much a direct swap.

Thanks for the help in advance.

- Greg

Rx-7Doctor

iTrader: (13)

Greg,

You need to perform a fuel pressure/quantity test first.

Crit

iTrader: (6)

Can you tell us more about the breakup?

I'd start with fuel, because it's easier to diagnose and you already have your suspicions.

1.) If you can ask around GRM, I'd think you can borrow a cheapo Air/Fuel ratio meter that you can sample from the ECU - that'll tell you if it's fuel delivery vs ignition. You don't need a wideband for diagnostic work, so the AutoMeter will do.

2.) One of my favorite diagnostic tools is an EFI pressure gauge (up to 80 psi or so), plumbed into a tee with 5/16 barbs running across the tee. Use about 3-ft of fuel line (1/4 or 5/16) between the gauge and tee. Attach a 5/16 fuel line to one end of the tee so that you basically have a male and a female at the tee, and the pressure gauge plumbed off of it.

You can pull the supply fuel line from the firewall, slip your new fuel line onto it, and attach the car's rubber line to the tee so you're sampling fuel pressure inline. Place the gauge under the windshield wiper, close the hood (don't latch it) and go for a drive. When your intermittent problem occurs, see if your pressure is fluctuating. You can also verify that the car's cutting fuel pressure at idle while you're at it.

If the fuel checks out, come back and we'll check ignition.


By the way, are you coming up for Zoom-Fest? If so, we can help you troubleshoot.

HadaGSL-SE

iTrader: (6)

The break up happens under load but not all the time.

The back story is that I got the car running and driving to take to a photo shoot and "track test." It performed flawlessly the first 170 miles on the motor. Didn't seem to have a whole lot of power higher in the RPM range. (Not that I was ragging on it too badly).

Once we got the the go cart track and it made a few laps it started having its problems. I pulled the intake to check the fuel injector connections to make sure they hadnt come loose. They were fine and the car continuted its behavior.

The break up is a hard miss then the power comes back on. It may or may not miss again if you keep your foot in it.

I'll see what I can do about testing the fuel pressure. Not quite sure how to test the quanity.

bliffle

Try Crits fuel pressure test. Just be sure you have all those fuel joints solid or you'll spray gas at 70psi all over your engine bay and then you'll probably blowup. Pretty colorful and exciting display. Too bad you won't survive to see the video. Tell your survivors to post the video here on the rx7club, though.

I got a good FI fuel gauge at Kragens for $55.

While at the autostore I also picked up some good FI hose clamps that put a band of unserrated metal around the neoprene hose so that it doesn't get cut and leak. Better than the cheapo factory clamps.

Rx-7Doctor

iTrader: (13)

The fuel quantity test is in the FSM. It's just a matter of seeing how much fuel comes out in a given period of time. :-)

gsl-se addict

iTrader: (3)

One thing that I've found is that the FSM doesn't explictly state the fuel volume test for the GSL-SE (it does for the 12A cars, though). However, there is a table (section 4B, I think) that does state the minimum fuel pump flow is 1700cc/min (1.7liter/min). Disconnect the feed line, stick it in a container with volume marks (or could use just an empty gallon jug). Turn on the pump and time for exactly 1 minute. At the end, you should have 1.7 liters or so (about 1/2 gallon).

This test doesnt have to be exact. If you are close to or over 1.7 liters, you are fine. If it is way under, you have a blockage or a bad pump.