Does anyone know what size Allen wrench holds the pump top on? I want to get a long ball end Allen socket to fit it and it has been so long since I did mine I can't remember what size it was. I would go check mine but it is pouring rain right now and I figure someone knows.

 

5mm. 8mm for the large allen on the throttle shaft. 4.5mm for the access to the guide pin oring. 10mm for the idle screws. 13mm for the fuel screw locknut. 6mm for the hex fuel screw, slotted if you have the other one. 17mm for the fuel return banjo bolt.

I prefer a T handle ball end allen for the 5mm. Works like a charm for the hard to reach allen.

 

I cut down an Allen key to reach that hard to get bolt after stripping one with the ball end. Never going to happen to me again.

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What do you mean faith I don't understand what did you cut?

 

Thanks for the info Bill

 

I just went through this...very frustrating. I spent more time trying to get that one allen key bolt loose...then it took me to swap the gov spring and get the top back on.

I tried cutting down an allen key, for a short stub, then put a small 5mm - 1/4" drive socket and extension...still didn't work. I finally just had to keep working at it from odd angles until I got it loose.

I was thinking of finding a regular hex head bolt for that location?

 

Snap on makes a very nice socket for this. Ask your local snap on guy what sockets he sells to the guys working on duramax's. 0.25" Chrome wobble 5mm. Works slick.

 

im about to attempt this again, and am worried about that one dam hat bolt.

 

I cut the short end of the Allen key.

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The cheap T handle ball end allen Craftsman set from Sears works great for me. After almost two dozen pump tops removed, it's still working great. Although I'm considering replacing it. It's starting to show some wear, but mostly because of all the stuff I read on the internet about ball end allens ..

 

The Snapon man came in today and he had a set of long ball end metric Allen sockets on special so I bought them. I will see how they work out on Saturday thanks for all the advice.