I JUST BUGHT A 91 1500 XTRACB 4X4 PICKUP. IT RUNS FINE BUT, WHEN I GET ON IT FROM A DEAD STOP IT BOGS OUT. SO I HAD A FRIEND BRING OVER HIS SNAP ON SCANNER AND MY ECM WILL NOT COMMUNICATE WITH THE SCANNER. MY FRIEND TELLS ME THE ECM IS BAD BUT I CANT UNDERSTAND WHY THE TRUCK DRIVES SO GOOD WITH A BAD ECM AND HE CANT TELL ME. DOES ANY ONE HAVE ANY INPUT ON THIS? ALSO IF I NEED A NEW ECM DO I NEED THE OE 7747 OR THE 8747 THE STICKER IS MISSING. THANK YOU FOR ANY HELP YOU CAN OFFER

 

that year truck uses the 7747 ecm. First thing I would do is try another scanner. Those snap on scanners are not the best scanners out there. Just swing by Autozone or Advanced and ask em to scan your ecm for codes. If you have multiple scan tools (or code readers) that won't communicate with your ecm, THEN maybe try to find out why there is no communication. But honestly, I don't think the data stream will show you anything related to your bogging issue, since it runs good otherwise. Just because there is no communication between the scan tool and the ecm, doesn't necessarily mean the ecm is bad. The bog from a stop is probably fuel related. Have you changed the fuel filter lately? If you decide to change the fuel filter, this would be an excellent time to check fuel pressure. Autozone has a nice fuel pressure tester kit that has an adapter that can be placed in-line for TBI engines. TBI press is 9-13 psi, almost always right at 13. Also, pressure could be good but low on volume. volume should be roughly a pint in 15 secs. these older trucks have that little piece of rubber hose connecting the fuel pump to the tank unit that likes to rot out and pump fuel back into the tank. Just something to think about if the pumps never been changed or it sat for a while. Hope this helps.

 

You realize this is the 3rd Gen F-Body forum? Maybe you should ask on a truck forum like

http://www.gmfullsize.com/forum/?

And take the CAPS off