1999 GMC Yukon 5.7 shakes after fuel pump install?

[Ethan Staggs]

Hey, guys!

 

 

I had a problem with my truck (1999 GMC Yukon 5.7 4x4 with around 200k miles) where it was hard to start, was bogging when taking off, and would not drop down a gear when under load and NEEDED to drop down a gear. I checked the fuel pressure and it was reading around 50psi. I got that reading after turning the key to on and then off position about 7 times. Obviously it's not supposed to 7 primes to get to 50 psi. Either way, when I went to start it, the pressure would drop to around low 40's. I replaced the fuel pump last night and drove it around for about 10 mins. Everything seemed fine and it had a lot better acceleration.

 

 

I get up to go to class this morning and it started fine, but I noticed it was shaking pretty bad. Pulled out of the driveway and it bogged going up the hill. Filled it up with gas thinking maybe I didn't get all of the water out when I was cleaning the tank last night, but it still shakes, ect.

 

Any ideas what it could be or where I should start looking?

[sahls01gmc]

Did you replace the fuel filter as well?

 

Water? Where did that come from? And how exactly did you clean the tank? And what was the purpose for that?

[Ethan Staggs]

Did you replace the fuel filter as well?

 

Water? Where did that come from? And how exactly did you clean the tank? And what was the purpose for that?

 

 

I replaced the filter recently, so I didn't figure that was critical. I'll replace it after class, though. The water came from me cleaning the tank out. All I used was water, and then used a shop-vac to get it all out. It wasn't dirty on the inside or anything, I was just trying to be thorough.