Mayt13

Hi Guys,

I finally got my new '89 IROC running right (tons of power) after replacing the mismatched injectors (also had a missing o-ring) installing a new egr and replacing the spark system.

At fist i suspected it was the power steering pump, but it has fluid and can make turns at full lock on idle. So it's not that.

Other threads have said it could be a lose ground/battery connection. I checked the battery connections, the ground to the passenger fender, block and the one on the back of the driver head; all good.

I'm wondering if it might be my fuel pump or fuel pump connections. The fuel tank only has one lose bad holding it up.

I don't understand how to access the tank or fuel pump. Do I really need to drop the rear suspension/differential?

How do I approach this issue?

Justin89Formy

iTrader: (26)

try it with at least half a tank of gas.

Also make sure your oil isn't low. if it is too low and causing you to lose oil pressure, it will cut off the fuel pump.

NowhereFast

My Iroc always stalled on right turns without at least 1/4 tank. I wouldn't be surprised if that was your issue.

Mayt13

Okay, I will fill her to a 1/3 tank and see if she still stalls. My dad is utterly convinced it's not a fuel related issue. He thinks the tank is moving and pulling on the fuel pump connections.

Mayt13

Update:
Ok, I hooked up a fuel pressure gauge and drove it around the block. It hits great most of the time, however when it does stutter you definitely see a 1-1 correlation with a drop in fuel pressure. It doesn't seem to just "shut off", but rather waver; sometimes worse than others. It also has stuttered (not as badly) in a straight line as well.

Is this just a dieting fuel pump or some type of electrical issue? How do I check the fuel pump circuits to rule that out?

Also, my gas tank is not bolted in correctly. Can someone give me a link to a thread explaining how to do the old school axel drop to get to the tank?

Bob88GTA

iTrader: (2)

Sure.....first get a case of your favorite beverage so when you and your bestest friend ever complete the job, and be successful, you can celebrate!

The fuel tank must be removed from the vehicle to replace the fuel pump on these models. For the home mechanic, this will require the rear of the car to be lifted quite high, because the exhaust must be either removed or lowered sufficiently to maneuver the tank out of the vehicle. First, drain or siphon the remaining fuel into a container to ease removal of the tank. Then, raise the vehicle and set it *securely* on jack stands; you'll be under there for a while, and you don't want these things falling on you while trying to jerk a filler neck hose off. Next, proceed in removing the exhaust. It is sometimes possible to remove the rubber hangers at the rear of the car and lower the exhaust sufficiently; however, removal may be more plausible. The differential must be dropped. This requires disconnecting the shocks, stabilizer links, and potential brake lines which need extending. Once completed, disconnect the electrical connector for the fuel pump, the fuel lines, the vacuum hoses, and the filler neck hose, making sure to mark or otherwise notate them so you remember which one connects to another. After this is completed, support the tank with a jack and remove the two fuel tank strap bolts. Once done, lower the jack slowly, manuvering the fuel tank to clear any obstructions. Once you have the tank removed, the fuel pump hanger assembly must be removed from the tank. It is held in with a lock ring, which can be removed with a screwdriver and hammer, tapping *lightly* on the ring until the slots align on the tank. Once the ring has been removed, the hanger assembly simply pulls out of the tank. Ensure that you do not bend or damage the swing arm on the hanger assembly. Then, remove the electrical connector from the fuel pump, and then the hose clamp. The fuel pump should then pull out of the bottom of the hanger assembly. And then, installation is the reverse of removal.

When complete, pop a top. Took me and my now x friend (kidding)about 5 hours.

And get a new sender, pulsator and EVERYTHING while its down. Walbro 255 pump is recommended.

Oh, and since you are there, pick out you favorite springs, shocks, torque arm bushings, and ANY other thing to replace and do it all. While its right there looking at you in the face, change that leaking rear diff cover and add new fluid!
All from experience, DONE!

Enjoy!

Mayt13

Half way into the job, let the differential down with the torsion beam attached, seems like I destroyed the already minced front bushing, whats the easiest way to replace this one? I can't get the bolts out they hit the trans tunnel.

Mayt13

Turns out it was the fuel pump after all. The doofus who owned the car before me let it sit with a poorly applied tank coating and no siphon on the fuel pump; no wonder it went out. It was easy to test for, I connected a fuel gauge to the rail, taped it to my windshield and watched the fuel pressure. Sure enough it dropped as soon as I made a hard turn or under severe braking.

Thanks Everyone!