Moving/flexing fuel pump
 

Hello all I have a 1986 Chevy c10 with a 305 motor and a mechanical fuel pump. With the engine running the fuel pump flexes/ moves in and out. Looking at it you would think the bolts are loose and its what the problem is but its not. All bolts are tight. is this normal? it looks like it has a heartbeat

Re: Moving/flexing fuel pump
 

Video?

Re: Moving/flexing fuel pump
 

http://www.youtube.com/watch?v=wt-K8...ature=youtu.be

Here is the link to the video the twitch can bee seen good at the 27-38 second mark.

Re: Moving/flexing fuel pump
 

I'm having a hard time seeing it. The truck sounds like a beast though. I don't think I would worry about it too much.

Re: Moving/flexing fuel pump
 

The bolts are to long. Put 1 washer under each bolt and that should fix it.

Re: Moving/flexing fuel pump
 

x2 on the bolts.

Re: Moving/flexing fuel pump
 

Thanks.....That is most likely what it is, because it leaked oil around the 1st seal I had put on, so I put another one on and over torqued the bolts and the leak stopped but maybe the flanged area is holding it tight enough to keep the seal but the bolt heads are not flush.

Next question they were the original bolts, its a new fuel pump could it be a improperly machined pump and that 1/32" difference can cause this?

Re: Moving/flexing fuel pump
 

I don't think those are original fuel pump bolts. Factory bolts used a unique bolt with a smaller than usual hex head for the size of the bolt with a washer head or captured washer. Length may also have been non standard. I can't seem to find any around the shop to get measurements off of. Hopefully, someone else will. If you are OK with the head size you have, the washer trick should work. If your local auto parts store has a "hot rod" wall, I'll bet you can find some in a Mr Gasket blister pack. Chip.

Re: Moving/flexing fuel pump
 

I will go to my hardware store and buy some shorter grade 8 bolts with some washers...I figured they were original, but like any good ole Chevy from the mountains they might not be... Crazy thing is I have a squeal on acceleration and ruled out everything even replaced the u-joints...now I have water vapor coming out of my exhaust only under load driving or with the wheels chalked and in drive.... So now I am following other gremlins... Probably due to me not re-torquing bolts after break-in with new head, head bolts, and head gasket. But I can smoke most stock vehicles... He he...unless the squeal is my rear diff..... in that case....:smoke: