db2 injector pump technical question

[vincentnova]

hi everyone

i have here a 1985 cucv that Im working on.
Im trying to understand few things here any help would be appreciate . thanks

question : with the engine off and with the shut off solenoid ON to let go the fuel in :
if you send fuel via ONLY an electric lift pump , does the fuel goes all the way up to the return port/line on the top cap of the db2 ?
or does the db2 pump has to rotate at the same time to have the fuel going all the way up to the return port/line?

thanks a lot

 

[Barrman]

You can get fuel to the IP with an electric pump. But, the engine and pump have to be turning for the fuel to get to the injectors. An electric pump only helps so far. Then it comes down to battery guts and starter health.

I replaced both fuel filter hoses and the filter on one of my trucks today. I pulled the pink wire, bled the filter, installed the pink wire and fired it up. It ran for about 4 seconds and died. As I knew it was going to With the entire hose from the filter to the IP full of air. I cranked for a count of 15, walked away from the truck for a timed 3 minutes. Repeated 2 more times. Then, on the 4th cranking session I gave it about half throttle and it started to jump around finally starting a few seconds later.

That was with only a mechanical lift pump. Electric pump will cut maybe 1 of those cranking sessions out. Here is a demonstration video:

 

[vincentnova]

thanks for this answer.
i removed the top cap from the IP , it is full of gas , everything is super clean inside
the return valve is clean as well
no matter what i do , i dont see gas going to the injector

all fuel line are good
return line as well

 

[Barrman]

Can you hear the solenoid clicking as you plug and unplug the pink wire with the ignition on?

 

[vincentnova]

Can you hear the solenoid clicking as you plug and unplug the pink wire with the ignition on?

yes , and also took it out and tested it , it is in working condition

 

[Barrman]

Fuel in the IP, fuel getting to the IP and no place for air to get introduced between the tank and the IP, right? That leaves you either need to keep cranking some more to get fuel to the injectors or you have internal issues with your Injection pump. How many seconds do you figure you have turned the engine over at full starting speed with no fuel at the injectors?

 

[vincentnova]

the truck was starting and drove fine.
i started to notice sometimes a lack of power wich lead me to do a complet overall lift fuel pump filter ect...
then truck runs well , even better
until it start to dies on me without any sign
it started well , warmed up well , go for a drive and quite on me couple times...until now it doesnt even start anymore

 

[Barrman]

Pull the check valve that the return line pushes onto. Look inside to see if it has little bitty black pieces up against the glass check ball. If it does, your IP will need to be rebuilt.

Near the end of this video the glass ball and black pieces is discussed:

 

[vincentnova]

i did that
when i looked inside i didnt see anything , and i clean it with carb cleaner