fuel pump question

There should be a 5/8" head bolt on the fuelpump, it should be facing the driverside framerail. Take the bolt out, be careful, there is a spring and a rod seated in the bolt. Put the small washers between the spring and the bolt head and put it back together. I have 3 small washers in mine, and I have 95 at idle, and 110 at 1800. It is hard to get back in with the washers in..

 

Before you think about shimming the pump you should try replacing your fuel bypass valve and make sure you are running the correct filters (another words enough flow through them). I run the CAT fuel filters on everything except my FASS system.

If you try those things with no improvement then I would suggest maybe trying to shim the pump. The plug should be on the pump facing the driverside frame rail. This plug is under pressure because of the sring inside, so when you remove it be careful not to lose any parts. Inside the plug and pump there will be spring, small rod, and a little round metal piece that sits in the end of the plug. Remove all the parts and place a small copper washer (I bought mine at ACE hardware, I can't remember the size, but it was the pretty much the smallest they had) with the edges ground down just enough for it to fit down inside the plug. Place the small round piece on top of the copper washer in the plug then reinstall the spring, rod, and plug back into the pump. MAKE SURE EVERYTHING IS CLEAN!!! After that just test your pressure and see if you need another copper washer. I highly suggest that you don't go over 120psi as sometimes to high of pressure will push fuel past the injector o rings.

 

84 psi is normal for MXS

 

The newest cat pumps have an allen key plug, its bit lower on the pump than the older ones, they have a larger diameter but thinner wire spring which you just stretch with your fingers. Dont go more than 120psi or you risk pushing your injector o-rings out.

 

i wa told 85 psi # idle 100psi # 18-2300 but mine is a 625

 

I would suggest shimming the spring over stretching. Once you stretch it it will go back to almost its normal size over time and also you are basically fatigueing the spring.

 

where could i get a good quality fuel press. gauge ......(just for my tool box)...... not in dash

 

snap on, matco. buy on line