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Need help identifying injection pump
- Thread starter Jred151
- Start date
On the Detroit Diesel 638 / VM 3.8, if fuel won’t go past the pump, the problem is almost always the mechanical transfer (lift) pump, not the injection pump. These engines rely on that low-pressure pump to feed fuel forward no supply there means no injection
Will L.
Well-Known Member
Someone is about to say something regarding attaching a fuel pressure gauge at the ip inlet…
MrMarty51
Well-Known Member
May I add that it could be most helpful to add a pressure gauge at the inlet into the IP ?
Welcome Aldis.
dbrannon79
I'm getting there!
I will second that notion! check fuel pressure from the lift pump. find the inlet fuel line going into the injection pump, if it's a rubber hose, disconnect it from the IP and plumb in a tee for a gauge. idk what the pressure spec is (probably around 7-8 PSI) also if you can, install a short section of clear tubing on the return or even the supply side so you can see if there is air in the line once its running and getting fuel.
as @Aldis1ne said, your engine has a mechanical lift pump. most engines with mechanical lift pumps are known to start leaking fuel into the block and mixing with the engine oil. there is a good chance that even with a new LP it can do this with all the chineesium crap made nowadays. you might consider bypassing the mechanical for a electric pump mounted on the frame rail. you can wire it in with a fuse and relay to keyed power fairly easily. and always keep a spare pump in the glove box, mechanical or electric.
as @Aldis1ne said, your engine has a mechanical lift pump. most engines with mechanical lift pumps are known to start leaking fuel into the block and mixing with the engine oil. there is a good chance that even with a new LP it can do this with all the chineesium crap made nowadays. you might consider bypassing the mechanical for a electric pump mounted on the frame rail. you can wire it in with a fuse and relay to keyed power fairly easily. and always keep a spare pump in the glove box, mechanical or electric.