Quick Fuel Pump Question

[Benscoter]

I have an 86 K10, and the other day my fuel pump bolts rattled out i guess. So i foolishly went to advanced and grabbed some 1 inch bolts that fit and put em on. Worked for about 10 mins and they fell out too.
Do yall know the size bolts for the mechanical fuel pump?

 

[chengny]

The fuel pump mounting bolts are 3/8' - 16 x 1 1/4" long:

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This refers to the fuel pump mounting bolts - not the spacer plate bolts.

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I would inspect the original bolts (i.e. the ones that "rattled" out). If the threads on those bolts are good, it would suggest that the internal threads (in the block) are what actually failed. If that is the case, replacing the mounting bolts most likely will not help the situation. You can try new bolts, but they will probably pop right out just like the other ones.

Hate to say it, but you are probably going to have to pull the engine and repair the block. There is enough meat around the mounting flange to allow you to drill the bolt holes out to the next biggest size (7/16 - 14 NC) and secure the pump to the spacer plate/block using 7/16" bolts.

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[Benscoter]

What sucks is when the first incident happened i was on a country road and couldn't find the bolts when they fell out.

So yeah i got some 3/8' - 16 x 1" long bolts the second time, thanks for the info. Lets pray its not the block but im gonna try tonight or tomorrow and put some 1 1/4 inchers in and give it a go.

Thanks man, Ill update tomorrow.

 

[Georgeb]

A there may be a metric size bolt a hair bigger that you may be able to tap theexisting threads to and get around pulling the engine a little research may save a bunch of time.
like M10x1.5 pitch

 

[chengny]

George, come on - would you do that to one of your engines? The major diameter of an M10 bolt is only a few thousands bigger than that of a 3/8" bolt.

If the threads for a 3/8 bolt have been ripped out, how can you expect to get a good cut with an M10 tap. It would probably just strip the remaining threads out and leave a hole.

And that's under the best of conditions. Consider the area he'd be working in:

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To even attempt to re-tap in place, he'd need a right angle drill extension and a ratcheting tap handle.

 

[Georgeb]

George, come on - would you do that to one of your engines? The major diameter of an M10 bolt is only a few thousands bigger than that of a 3/8" bolt.

If the threads for a 3/8 bolt have been ripped out, how can you expect to get a good cut with an M10 tap. It would probably just strip the remaining threads out and leave a hole.

And that's under the best of conditions. Consider the area he'd be working in:

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To even attempt to re-tap in place, he'd need a right angle drill extension and a ratcheting tap handle.

Your right, thinking it through more it's not a good plan. Your suggestion to go to the next size up is better and yeah thats gona be a bitch of a spot to work in. Thanks for the correction!
Sometimes my redneck leaks out if I don't do my therapy. Good thing for the accountability circle LOL!