Hummers: m1009 fuel system, shaft seals, throttle shaft


Question
I have a 84 Mil. Blazer, It is hard to start the first time. The fuel is draining back to the tank. I have replaced the check valve behind the fuel filter. this worked great for 2 weeks. I now am thinking of removing the manual fuel pump and putting on an eclectic pump. What type should I use and What psi? Can I keep the manual pump and just add a elect. pump somewhere in the system?

Answer
Burt,

If a 6.2 developes a hard to start condition after not being ran for a while and the glow plugs are operating properly the problem is usally at the injector pmp. The throttle shaft on the injector pmp has o-rings that wear over time. Sometimes they will leak fuel, or they will allow air to enter the fuel system; causing loss of prime in the pmp. Finally causing a hard start.

Check all other fuel lines to ensure they are tight before condeming the throttle shaft seals. If the seal are bad which is common, you can purchase a throttle shaft seal kit from a GM dealer. You will also need intake gaskets. the whole procedure should take about 3-5hrs. It will be necessary to remove the cap off the inj pmp to get the throttle shaft out. Be careful when you remove the long allen head bolt from rear of pump that it does not break. Soak it with penetrating fluid.

I do not recommend replacing the fuel pmp or otherwise changing the fuel system delivery.