Anyone replace their fuel pump?

[FLYNAVY30]

Ive got the factory 402 in my C20 and it appears the fuel pump just quit. For the past few weeks, the truck has been exhibiting all the signs of a mechanical pump going bad....stumbling on acceleration, multiple attempts to start, etc.

The motor cranks over fine, oil pressure is good, and all 8 cylinders are getting spark. When I pour gas directly into the carb, it lights off for a few seconds and then dies so the only thing I can think of is a bad fuel pump.

Ive never changed a mechanical pump before....any tips or gotchas to be aware of?

[LockDoc]

-
It can be hard to get the rod in position and keep it there while installing the pump. I put heavy grease on the rod to hold it in place.

Some engines have a bolt hole that lines up with the rod so you can screw a longer bolt in it to hold the rod while you tighten up the pump. I don't know about the BBC though. They can be a pain in the rear.

You might get a better response if you PM a moderator and have them move this thread to the "Engine and Drivetrain" forum.

LockDoc

[FLYNAVY30]

ok, thanks for the help, headed to autozone now

[GMCjunkie]

I just changed mine, that rod is an absolute pain. The guy at the auto parts store told me to use a large thin rubber band to hold up on the rod until you get the bolts started, then just cut the rubber band and pull it out and finish tightening your bolts. Worked like a charm!! Good Luck !!

junk

[FLYNAVY30]

thanks for the tip....picked up a new pump today...gonna do the work on Saturday morning

[GMCjunkie]

How did it go?

[FLYNAVY30]

Man was that a pain in the ass! Even with all the advice, it still took the better part of the afternoon. For starters, my truck also has factory A/C, which was right in the way of EVERYTHING. Since it didnt work, and Im going to switch to a vintage A/C system when I swap the motor for the 327 LS Im building, I ended up removing most of the system now to gain additional access. Additionally, I really didnt have a full understanding of how the pushrod worked. Had I had a better mental picture (entirely my fault for not turning to you tube sooner), it would have been much quicker. Once I figured out how to back off the bolt at the bottom to remove the pushrod completely, then grease it up, and push it ALL the way up into the chamber with a screw driver from the bottom, the rest of the install went much smoother.

That being said, it fires up much better now, and drives significantly better. All along, I thought I needed to tune the carb when in reality, the pump was probably going bad all along.

Thanks again for the help guys!

[GMCjunkie]

Yeah, cant anything be easy, lol, that would just be to... well... easy. So glad you got it though.

[FLYNAVY30]

yea I hear ya.....Im looking forward to this engine/AC/trans swap though....at least at that point I will have installed most everything on the truck, so I will know how it got there and how to fix it!

[GuyO]

Flynav30, I just did the exact same thing on my 72 GMC C2500 with a 402. The square bolt on the block under the pump was the key to the rod. Take that out and the rod falls out into your hand. I greased it to help hold it and a punch to push it back up into position then installed the new fuel pump. The other problem was getting the 7/16" bolt into place on the back side. With all the obstructions from the AC and trans cooler lines it took me about 3 hours to change the fuel pump!

[68 TT]

A little late but maybe it will help the next guy who finds this thread.

Putting the timing mark on TDC will put the fuel pump eccentric on the low spot making it far easier to install the mechanical fuel pump.

I also use a magnetic pick up tool on the pushrod to hold it back so you can get the end of the fuel pump arm behind it. Once in place you can easily pull the pick up tool off the pushrod with the fuel pump in place. After that that bolts go in easily.