91 hesitates when hot

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Apr 7, 2009
Austin, TX
This forum is bad ass...thanks for all of the help you've already given me. So, i've had my 91 fj80 for a couple of months. When i got it, there seemed to be very little power and intermittent hesitation while driving. According to the shop, i needed an igniter, egr modulator and switch valve, as well a timing check and fuel filter. I bought a used igniter from cruiserparts.net and replaced the egr modulator and switch. This improved the performance to a large degree BUT....after driving for 20 minutes or so in the afternoon heat, i start to get some hesitation. I'll push the gas pedal down, and nothing really happens.

Engine compression tests all came back good. Could it be the timing or fuel filter? any ideas? thanks a bunch.
Try replacing the filter in the gas tank. It really helped my 91. Mike
sounds like you need to upgrade the wire to for the EFI main relay. my 92 had sim. issues. would also not start when it gets hot outside. do a search for EFI main relay. HTH
Try replacing the filter in the gas tank. It really helped my 91. Mike

Agreed. There is a pre-filter on the fuel pump that is good for 100K miles. Sounds like fuel starvation to me.

Typical EFI relay/wiring failure would shut the motor down (no spark).

You guys were on the money with the fuel filter. It was a mess. We replaced it, but still only getting about half pressure. The fear is that there is more blockage in the actual fuel tank from corrosion, so the next step I guess is removing it to take a look. Before i purchased it, it had been sitting around with about a quarter tank of fuel. We'll see where this takes us...
---UPDATE 2---

You guys should have seen the sock on the fuel pump and the screen from the tank. It looked like a volcano erupted in my gas tank. This truck spent some time in south Texas and the red dirt down there somehow found its way into the gas tank. Oh...and the last person to change the fuel filter installed the new one backwards...nice. The guys at the shop think someone was using an old farm gas tank to put gas in it. New filters and fuel pump. Pressure is back. Many thanks to you guys for your insight. Maybe I can help someone else down the road...
Glad to hear the issue was resolved.

Did you clean out the fuel tank?

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