[jjhayden]

Hello all. I have 1991 trooper that I just purchased and am in the process of fixing. It has the 4 cyl 2.6 engine in it. Upon starting, it starts fine, then sputters out and dies.It will also stall at lights.It will only stay running after it is warmed up some, but if i turn off hte key and try to restart it will start then sputter out and die. I have changed the spark plugs, checked the firing order, new air filter, and tried to pull codes, but all i get is code 12. When it is at full speed I get no hesitation, it runs fine, but at idle, it runs very rough. Where is a good place to start? Thank you, Jeremy Hayden

 

[squatch]

Welcome to the planet. You most likely have a bad alternator. Instead of writing the whole story out again I'm going to ask you to do a search. sometimes it wroks better to search from giggle with planet isuzu as part of your search. I'm lazy today. Several threads will have the test procedure and explaination

 

[shooter]

One of the reasons he speaks of the alternator is that after starting, the alternator provides power to the fuel pump. The pump runs off the battery for about the first 15 seconds or so and then that responsibility is handed off to the alternator. You can also try swapping the fuel pump relay with a like relay to test the relay. The a/c relay might swap out. Don't use a relay which is needed for the trooper to run.

 

[Rhodes]

When the alternator on my '90 went bad, it didn't quit charging, so I just jumped the fuel pump fuse over to...something else, I don't remember what. Works fine, still. One of these days, I'll pull the alternator and fix it.

 

[Hack]

This post viewtopic.php?t=13176 tells you how to bypass the relay. With the circuit jumpered, the fuel pump will get power all of the time INCLUDING WHEN THE KEY IS OFF. But it will allow you to at least see if you have the problem that everyone is discussing.

 

[squatch]

This post viewtopic.php?t=13176 tells you how to bypass the relay. With the circuit jumpered, the fuel pump will get power all of the time INCLUDING WHEN THE KEY IS OFF. But it will allow you to at least see if you have the problem that everyone is discussing.

Thanks for the link. I've been meaning to print that pic off for some time. I'll bring that and my switch on Sat!

 

[Hack]

Thanks for the link. I've been meaning to print that pic off for some time. I'll bring that and my switch on Sat!

I keep a copy of the photo and the jumper in the glovebox of the Trooper.

 

[jjhayden]

Hell all! Thank you all for the information you provided. Upon thorough examination of the engine this weekend , we found several things wrong. See, I had just bought this vehicle and it appears that somebody may have tried to fix some things themselves and did not put stuff back together properly

1.found vacuum hoses not attached
2.the oxy sensor was bad, tested it with a voltmeter, although no check engine was found for it, it still tested bad
3.the back pressure transducer was shot
4.the timing was way off, it seems someone put the rotor in a couple of teeth off
5.the lash on the rocker arms was not set, they had them over tightened, cause the valves to stay open

Now she starts right up, with no problems.I guess i should have checked all those things first before asking for help

 

[squatch]

That's what we are here for. Glad you got it straightened out!

 

[Hack]

Glad to hear you worked it out.

1.found vacuum hoses not attached

With the miles of vacuum hose on the 2.6L, it is a good idea to replace all of it. Most of us already have.

2.the oxy sensor was bad, tested it with a voltmeter, although no check engine was found for it, it still tested bad

There is an O2 light but it is just operated by the speedo and will come on every 90,000 miles. The ECU will not detect a bad O2 sensor.

 

[Selahdoor]

There is an O2 light but it is just operated by the speedo and will come on every 90,000 miles. The ECU will not detect a bad O2 sensor.

I checked my 88 2.6 ECU a couple days ago for codes, and the only code it came up with, was for the O2 sensor.

 

[Hack]

There is an O2 light but it is just operated by the speedo and will come on every 90,000 miles. The ECU will not detect a bad O2 sensor.

I checked my 88 2.6 ECU a couple days ago for codes, and the only code it came up with, was for the O2 sensor.

That is news to me. I have had the O2 light go on and all you do to turn it off is to flip a switch behind the speedo. The light is totally related to mileage. In fact, you can turn the light on by also flipping the switch. Never heard of the CEL going on due to the O2 sensor.

 

[Selahdoor]

That is news to me. I have had the O2 light go on and all you do to turn it off is to flip a switch behind the speedo. The light is totally related to mileage. In fact, you can turn the light on by also flipping the switch. Never heard of the CEL going on due to the O2 sensor.

My CEL light goes on occassionally. Usually in a situation where the motor is being bogged down.

So, I checked the ECU.

The only code it showed was 13. Which is:

13 - Oxygen sensor or circuit

 

[nctrooper]

There is an O2 light but it is just operated by the speedo and will come on every 90,000 miles. The ECU will not detect a bad O2 sensor.

I checked my 88 2.6 ECU a couple days ago for codes, and the only code it came up with, was for the O2 sensor.

That is news to me. I have had the O2 light go on and all you do to turn it off is to flip a switch behind the speedo. The light is totally related to mileage. In fact, you can turn the light on by also flipping the switch. Never heard of the CEL going on due to the O2 sensor.

i know this is a old thread but it just answerd my problem of the O2 light so :mrgreen: