cant go highway speeds

[jared]

Wow guys thanks for all the info, I posted this on another forum and only got one reply.

As far as exhaust goes I do not have cats, just pipe and a flowmaster.

When I first got the truck it was spraying gas from where the FPR connects to the fuel rail. I replaced the O ring but the whole unit might be bad. Is there an easy way to check it?

How do I pull codes without a reader? Is their an article on here explaining how to do it? I will search for it.

I am not sure if the truck is actually backfiring or not... I dont know how else to explain it loud constant pops from under the truck.

I put the truck on jackstands and ran it through the gears. It shifted smooth and ran like it should. So it only happens when the truck is under full load.

When I first got the truck one of the exaust manifolds was basically shattered, I replaced it but wondering if that could have caused any issues?

 

[RyanL]

Sorry I didn't post back for a few days, but like I said about the FPR - just pull the vacuum line off of the rear of it while it's running and see if any gas drips out of the back of it. The exhaust manifold crack is a good question. While I've driven a few vehicles around in the past with leaking or cracked exhaust manifolds for short periods of times without issue, I have heard that it can burn out a valve. I don't know how true it is, but I can't imagine that backfiring could be good for valves either. As far as pulling codes, yes it can be done on our vehicles without an OBD reader. Here is the link. Just scroll down to the malfunction indicator method of testing. I have a newer Nissan which I can do the same thing with (actually doesn't even require a jumper wire) and it's a bit more comprehensive (the first digits of codes are long flashes), but give it a few tries and you'll get the hang of it. There's links to the codes are at the top of that page. Good luck.

 

[jared]

Ok guys I pulled the codes and it looks like it is going to be a fuel issue.

The codes I got are:

41-system lean
53-Throttle Position sensor too high
63-Throttle Position Sensor signal too low
87-Fuel pump circuit fault (check inertia switch) - Power / Fuel Pump Circuits

so by the 53 and 63 I would guess that the TPS needs to be replaced.

I am not sure about the 41 and 87 would the TPS make it run lean? If the inertia switch was out wouldn't it shut down the fuel pump totally? I used to have an explorer that Would not start untill I pressed the reset button on the switch.

 

[RyanL]

If the inertia switch was out wouldn't it shut down the fuel pump totally?

No one ever said that our ECUs were smart, maybe it's cut in and out a few times or something because of bad contacts on a switch, a bad relay, or a number of wiring issues. You may have your hands full trying to track down that issue. Personally I would pursue the TPS first because that can cause issues. I'm not sure how much one costs, but I would test it first to see if it is in fact bad. You can test the sweep with a digital multimeter if you move the throttle plate real slowly, but is much more accurate with an analog multimeter (one with a needle). I wouldn't totally dismiss what that other guy Dave90Ranger stated, but he pointed you in the direction of the fuel pump. What he failed to mention is that he replaced it and it still didn't do the trick; just check his thread out. Just don't go throwing any parts at it unless you're sure.

 

[jared]

The TPS is only 35.00 at auto zone so I will probably just replace it. Would the TPS cause it to run lean? I had a feeling that the fuel pump issue was going to be a pain to figure out