Ok Guys.....need some directions to start. I had a fuel pump go bad Saturday on my 95 s-10 Blazer. Got it home and put in a new fuel pump. After I put the pump in it started right up and went down the road just like it is supposed to. After about 8-10 miles it starts sputtering under a load and won't take the fuel. Now here is the kicker.....you can put it in neutral and shut it off, then restart it in less than two seconds hit the gas and go another 8-10 miles then repeat. I have changed the fuel pump, checked for kinked vent lines and even run with the gas cap off with the same result. I scanned the computer and no codes hard or soft that would indicate a fuel or ignition problem. I haven't checked the fuel pressure yet on the blazer. I am going to put a guage on it this evening and drive it until it starts acting up and see if I have any drop in pressure. Anyone else ever run into a similar problem or have an idea of where to start looking? I am grasping at straws. BTW.....what is normal fuel pressure for this model w/4.3???

 

What brand of fuel pump did you put in?

I *think* the spec is koeo 60-64 psi. I know you need at least 60 psi for a cold start.

 

Also - sometimes fuel pumps are sold faulty. For this reason it is recommended that you don`t settle for less than the AC Delco pumps. However, if you can confirm that the new pump is good, you should also check the fuel pressure regulator. If you run a search, this has been discussed in depth elsewhere on the Forum. Good luck!

BTW - Hi, Leeann!

 

Yep, that's why I asked what brand of pump

Hi, Raphael!

 

Yeah, I figured that`s why you said that. Just adding more info to what you were saying.

My buddy and I replaced my fuel pump last summer. I can`t think of a worse PITA EVER! [:@]

 

This sounds like it is a problem when the PCM transitions into closed loop operation. Once you have verified the fuel pressure, I would have a look at the I/O's of the PCM. Something may be dropping out when it hits closed loop. It may be a PCM problem.

 

Well, it isn't a fuel pressure issue. I have about 60lbs at startup and after it warms up it doesn't go below 54 lbs. The problem arises at about the same time every time, when the outside temp is cooler it will go about a mile more before acting up. The ECM is not showing a check engine light but at the time I don't have a scanner that will scan the OBD I ECM. I will get one this evening and check it out but if the Check Engine light isn't on there should be no code logged should there?

Swartlkk....you'll have to forgive me, I am a shadetree mechanic. My real joy is building old hot rods. Not many of those have a PCM. When you mentioned that something could be dropping out when the PCM is going into closed loop operation, do you think that I have a faulty computer or a faulty sensor. Something that doesn't make sense to me at all is how fast it recovers. I can be driving down the road at 60 mph and when the problem presents itself I can shut the ignition off, restart and within just a couple seconds drive another 6-7 miles before the problem starts again. The time between restarting and the problem beginning again doesn't change.

 

I had originally thought this problem that I am having was something that was occuring all at once, but it isn't. It is coming on gradually but quickly. Starts out hesitating at full throttle and then gets worse the longer you drive. It will progressively get worse until it won't take fuel at all.I checked the values from the TPS that I found on one of the other threads. I did finally find a thread from a guy that had similar problems to mine. His ended up being cured by replacing the spider and FPR. I don't have a MAF sensor so is there any way to check the MAP sensor? What other sensors would cause this problem? I am still leaning towards a PCM problem since it recovers so quickly. I wouldn't think that a FPR would be likely to cause this problem. My logic (however faulty it is) tells me that if a FPR is bad, thn I should have consistant poor performance. I don't see how killing the ignition then restarting could cure it. All of your help is very much appreciated. OH....BTW......it is a Delco pump!!

 

I think I may be talking to myself.....I don't even hear the voices anymore.

 

Wow... You know, that reply just makes me want to take the time out of my busy day to help you... Have some patience. Cya.