87 LS MONTE 4.3 ENGINE TROUBLE, HELP

[lakewood213]

MY 87 4.3 RUNS, DRIVES, AND IDLES GOOD, HOWEVER AFTER DRIVING IT FOR A WHILE, LIKE AN HOUR OR MORE, IT WILL LOSE POWER LIKE IT IS GETTING CHOKED FOR FUEL. WHETHER I AM DRIVING OR STANDING STILL. WHEN IT IS DOING THIS I CAN PRESS THE GAS PEDAL AND IT ACTS LIKE IT IS GOING TO STALL. IF I TURN THE KEY OFF AND START IT RIGHT BACK UP, ITS FINE AND RUNS NORMAL UNTIL THE NEXT TIME IT DOES THIS. I HAVE CHANGED THE INLINE FUEL FILTER, BUT NO CHANGE. I NEED SOME INFO. HERE BEFORE I GO REPLACING MORE PARTS THAT I DONT NEED. I HAVE ALSO USED FUEL CLEANER ADDITIVES WITH NO LUCK. THANKS IN ADVANCE FOR SOME INSIGHT WITH THIS

 

[85GPLef41]

hook up a fuel pressure guage and see what the pump is putting out..

 

[dogsht]

As voltage drops due to age deterioration of factory weak wiring & connections.. pump output drops. This is a common problem with these and more notably the turbo Buicks which have the same basic setup. Often a problem solver for your description and regardless a great upgrade is to direct wire fuel pump power from the alternator. Naturally if your pump is shot its shot but it may just be weak due to voltage drop. A good body ground is also good. Racetronix site and GNTTYPE.org had instructions and diagrams for this but most do it at the time they upgrade there pump such as with the Walbro 255LPH. This pump is overkill for your current application but depending on planned future upgrades may be money well spent.

 

[mhsmonte]

hook up a fuel pressure guage and see what the pump is putting out..

Do this first because I bought a cheap fuel pump from ebay because it claimed that it could put out the pressure the ls engine required and after about a week of stalling at stop lights, I decided to check my fuel pressure and it would drop to about 5 psi lower than the required pressure... So I bought a Walbro 255LPH and it works perfect.

 

[lakewood213]

i really appreciate the input, gonna have to check it out. hopefully this solves the problem. its a very solid car, hasnt even hit its first 100,000 miles yet