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GMC 6.5 Dually

@Redtruck97
You NEED to meet up with him. Ferman is a rockstar on these.

Awesome, I can help you. I am off chancy road in settlers rest RV resort...I work 6am-6pm 5 days a week in Tampa, I can meet this Friday after about 1030 or sat-sun what works best for you. Not sure how far the truck will make it or it might not stop at all. PH# 478-288-7778 and thanks
 
THANKS GUYS FOR ALL THE HELP WITH THIS, I'M SURE WE WILL FIND OUT THE PROBLEM. IF I NEED A PUMP I MIGHT TRY TO GET THE NEW ONE AND CONTINUE TO KEEP FIXING THE TRUCK UP. YOU GUYS ON HERE ROCK AND SURE GLAD I FOUND THIS SITE....HOPE THE FERMANATOR WILL CONTACT ME.
 
His optic sensor and/or the optic disc inside are shot. At idle the fuel rate is bouncing from 0-2 mm3 of fuel, touch the throttle and it goes nuts. Unplugged the optic, start it up, and it idles good, have to give it quite a bit of throttle, then it would still shoot up. Plugged his original apps in and I could semi control the throttle. It has a blue tag 5521 pump on it, doesn't look that old either. What us weird is if you raise the idle with the tech2, it would go up smoothly regardless of the fuel rate displayed, but with the apps it would go nuts. The solenoid closure time stayed steady around 1.85(as slightly high) and the only code was for boost performance.

Also found ZERO vacuum from his vacuum pump. And his cluster problem is the left side is out, so either a broken ground or bad power. I know the right side of the cluster grounds at the back if the intake, but I for the life of me can't remember where the left side grounds to. And my disc doesn't have 97 wiring diagrams, only 98-05.
 
With the scan tool plugged in, not the apps thing, the scan tool will complete at least one ground circuit. That is what could be causing the erratic engine response.
For one example.
A friend over here has a GMC Envoy, a 2015 IIRC.
He went to the post office, got done in there, fired it up, stepped on the brake, could not get it into gear. After several attempts He calls Me. I asked him if he had his code reader along, yup, told him to plug it in and see if there is any codes. No codes, He left it plugged in, tried the brake pedal, went right into gear. As long as he had the reader plugged in, all was fine. I told him it is a bad ground somewhere in the circuitry. He took it over to the local transmission shop, YUP, they found a bad ground connection, I cant remember if it was within the console or under the dash. He has not had another problem with that portion of the vehicle since.
My suggestion is to get under the hood and clean every ground available. I used a dental root canal file and cleaned every connector at the back of the engine, along with every ground I could find and even added more grounds from the engine to the body and engine to frame.
 
With the scan tool plugged in, not the apps thing, the scan tool will complete at least one ground circuit. That is what could be causing the erratic engine response.
For one example.
A friend over here has a GMC Envoy, a 2015 IIRC.
He went to the post office, got done in there, fired it up, stepped on the brake, could not get it into gear. After several attempts He calls Me. I asked him if he had his code reader along, yup, told him to plug it in and see if there is any codes. No codes, He left it plugged in, tried the brake pedal, went right into gear. As long as he had the reader plugged in, all was fine. I told him it is a bad ground somewhere in the circuitry. He took it over to the local transmission shop, YUP, they found a bad ground connection, I cant remember if it was within the console or under the dash. He has not had another problem with that portion of the vehicle since.
My suggestion is to get under the hood and clean every ground available. I used a dental root canal file and cleaned every connector at the back of the engine, along with every ground I could find and even added more grounds from the engine to the body and engine to frame.

Thanks yes I will doing all that. I will update as we go along.
 
OK guys I pulled the trigger and ordered a pump, hope it gets here soon and I will start to disassemble this beast. I will update the progress. The truck is rust free and not in bad shape so I will fix and keep it going. Thanks again for all the help and advise.
 
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