3208 fuel issue

bam1968

Member
HI. I have a mid '80's ford dump truck with a 3208 in it. My issue is that if it sits for a week or longer it basically seems to lose it's prime (fuel). It will start right up and idle for about a minute or so. Then it starts to miss and flutter until it eventually dies. If I pump the hand pump before I start it then it starts and mostly runs fine. My question is, is there a check valve or something that is supposed to keep the fuel from bleeding back to the tanks? Thanks in advance for any and all advice.
 

Truck Shop

Well-known member
Normally on cat the primary filter base which includes the primer pump will have a check valve. There is also one built into the primer pump base
if I remember right.


Truck Shop
 

bam1968

Member
Thanks Truck Shop. A couple months ago I did switch out the primer pump for one a used one I had sitting on a shelf. So, there is a chance it could be bad as well. This motor has one of those square glass filters on the other side of the engine (right side). The fuel runs through it first and then over to the spin-on filter with the primer pump. I will take a look at it again tomorrow. Thanks Again
 

rodneyp10

Member
Thanks Truck Shop. A couple months ago I did switch out the primer pump for one a used one I had sitting on a shelf. So, there is a chance it could be bad as well. This motor has one of those square glass filters on the other side of the engine (right side). The fuel runs through it first and then over to the spin-on filter with the primer pump. I will take a look at it again tomorrow. Thanks Again
The throttle shaft seal is worn and allowing air that causes fuel drain back.
 

Longhood

Well-known member
If the fuel was leaking back at the throttle shaft, the truck would probably not start or would die immediately, on a Cat system, I would lean towards the primer pump check valve.
 

Truck Shop

Well-known member
Normally if the check valves flip in the primer pump on a cat it will cut fuel off and kill the engine, I'm leaning toward crap stuck
in the old primer pump check valves in that used primer he put on.

Truck Shop
 

bam1968

Member
First off I want to thank you guys for your input. I should mention that when I intially changed the primer pump awhile back that it didn't seem to help or hurt the overall problem. As a rule, if it has been sitting for awhile, if I pump the primer pump until it gets a fair amount of pressure against it before I intially start it. It will then start a run just as it should. I can shut it off and restart it with no issues all day. A few days ago I asked my helper to go start it (he is the one that normally drives it) and he did so without priming it. So, basically within a minute or two it starved itself for fuel and died. So, I went out and started operating the primer pump with little success until i cracked the line going from the filter base to the fuel pump. Then finally it started pumping fuel. I tightened the line and pumped the primer until it got a good amount of pressure against it. After going through that process 2 or 3 times and with a little sniff of either got it to start but wouldn't run much over an idle with the throttle wide open. Sounded like it was just trying to work the air out of the system but couldn't. Then it got dark and that's where I'm at right now on it. I am planning on messing with it this afternoon and will post any updates later. Thanks again.
 

bam1968

Member
Well I think I may have found the problem. Basically directly above the injection pump there is a petcock that you can open to purge the air while operating the hand pump. It seems that the petcock was not closing properly and allowing the fuel to drain back to the tanks. I guess time will tell if this was the problem. Thanks for the input.
 

Truck Shop

Well-known member
Good for you. Sometimes it's the simplest stuff. Good you found it before spending tons of time and money.

Truck Shop
 
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