cold cranking

[FlatBlackBurb]

i have an 87 suburban with a 5.7 TBI motor. i'm replacing the fuel pump tomorrow because of another problem but i just wanna know something... and my truck has always done this.

before a cold start, i'll cycle the key a couple times and let the fuel pump run, then when i start to crank it, it cranks pretty slow. not like it's gonna die slow but much slower than my '93 sierra with the same engine. it takes about 5+ seconds to turn over. when the engine is hot it cranks a little faster but i usually have to crank it the same amount of time to get it to turn over. and here's whats weird: i replaced the starter when i first got the truck, about 3,000 miles ago and i replaced the battery at the same time. could there be something i'm just totally missing here? thanks

 

[4X4HIGH]

i have an 87 suburban with a 5.7 TBI motor. i'm replacing the fuel pump tomorrow because of another problem but i just wanna know something... and my truck has always done this.

before a cold start, i'll cycle the key a couple times and let the fuel pump run, then when i start to crank it, it cranks pretty slow. not like it's gonna die slow but much slower than my '93 sierra with the same engine. it takes about 5+ seconds to turn over. when the engine is hot it cranks a little faster but i usually have to crank it the same amount of time to get it to turn over. and here's whats weird: i replaced the starter when i first got the truck, about 3,000 miles ago and i replaced the battery at the same time. could there be something i'm just totally missing here? thanks

Have you replaced the battery cables? Have you made sure that ALL grounds are CLEAN and TIGHT? Also if you have to crank it a bit for the engine to start you might have a bad fuel pump relay. That is the typical sign of a bad FP relay. Can you hear the fuel pump cycle for 2 seconds when the key is first turned to the run position?

 

[FlatBlackBurb]

well i'm going to replace the fuel pump tomorrow anyway, so i might as well replace the relay. everything's pretty solid in the cable department, just to be sure i'll check the starter and everything tomorrow just to see whats up.

.... fuel pump relay... never woulda thought of that. once again 4x4high you know the answer

and yeah i hear the pump run for 2 seconds both when i turn my key to "on" and when i shut my truck off.

 

[4X4HIGH]

well i'm going to replace the fuel pump tomorrow anyway, so i might as well replace the relay. everything's pretty solid in the cable department, just to be sure i'll check the starter and everything tomorrow just to see whats up.

.... fuel pump relay... never woulda thought of that. once again 4x4high you know the answer

and yeah i hear the pump run for 2 seconds both when i turn my key to "on" and when i shut my truck off.

If you can hear the fuel pump cycle when the key is first turned to the run position then the FP relay is working.

Battery cables go bad from the inside out usually. If they haven't been replaced i would highly suggest you replace them.

 

[dyeager535]

I'd leave the relay alone if you hear the pump run. Wait until you replace the pump, see if the problem resolves itself.