1086D starves itself

After replacing both fuel filters it will run from 20 seconds to 11/2 minutes and die. The longer
between startups the longer run time. After initial start up it will just spin. Then took off rubber
supply line from filter housing to pump and no flow. Took off secondary filter and no flow. Cracked
primary filter and fuel rushes out. Therefore would seem to me that theres an obstruction in filter
housing. Dont want to take housing off block to clean if I dont have to. Anyone run into this
problem and if so what did you do? Thanks in advance.

(quoted from post at 03:33:03 05/02/21) After replacing both fuel filters it will run from 20 seconds to 11/2 minutes and die. The longer
between startups the longer run time. After initial start up it will just spin. Then took off rubber
supply line from filter housing to pump and no flow. Took off secondary filter and no flow. Cracked
primary filter and fuel rushes out. Therefore would seem to me that theres an obstruction in filter
housing. Dont want to take housing off block to clean if I dont have to. Anyone run into this
problem and if so what did you do? Thanks in advance.

Click to expand...

Well you have done a good job of isolating your problem and are very fortunate that it is so easy to get at. I'll bet that you can save hours by biting the bullet and removing the housing.

When did engine last run? If it's been awhile there are two valves in the supply pump that might be stuck. First is the INLET line nylon check valve, remove the line and use a small screwdriver or nail to knock it inward, it MAY be stuck on it's brass cage seat. You should feel it move about 1/4 inch. Next is the pressure regulating valve under the steel hex cap on side of the pump, takes a 7/8 inch wrench. Remove the cap, spring, and see if the steel valve inside is stuck. It SHOULD come out when using the hand primer, or a magnet. If it's stuck, I've had luck getting it out with a pair of external snap ring pliers, it MUST move freely. I doubt you have a filter base problem..

Ok but why no flow past primary filter. It actually was running about 2 weeks ago and started this after I changed filters.

Maybe something wrong with the filter, if it ran fine before. Does fuel come down TO the left, supply pump inlet from the first filter?

Had a guy dad was getting wood from had a 584 or such, there was a plug in the fuel filter mounting casting. It was a slug of like silicone or some goo that had to be pulled/flushed out to get fuel flow. I would clean the filter base out first then try the pump choices. OF course if the fuel goes from tank to filter, to low pressure pump, to second filter to injection pump then it is all changed.

Had the same problem with a Ford there was a 9/16 plug on the filter housing. took it out ran a small drill bit through it ran perfect after that.

Just because there is fuel in the primary filter when you take it apart, dont automatically assume that there might not be an obstruction in the fuel tank or line leading to the filters. I would start at the tank and move forward. Been down this road before

(quoted from post at 05:33:03 05/02/21) After replacing both fuel filters it will run from 20 seconds to 11/2 minutes and die. The longer
between startups the longer run time. After initial start up it will just spin. Then took off rubber
supply line from filter housing to pump and no flow. Took off secondary filter and no flow. Cracked
primary filter and fuel rushes out. Therefore would seem to me that theres an obstruction in filter
housing. Dont want to take housing off block to clean if I dont have to. Anyone run into this
problem and if so what did you do? Thanks in advance.

Click to expand...

Troubleshooting 101-First thing to check = The last thing you touched.

-Sounds like you are getting some fuel to the injection pump, also sounds like you may be getting air along with it.

-Cracking loose the primary filter and seeing fuel present is an indication that fuel is making it's way from the tank to the filter housing, it is not an indication the primary filter is filling, nor is it an indication you have a constant flow. (obstruction in tank, plugged vent cap, crushed line or hose...)

-You know it was working with the old filters so go back a step and reinstall the old primary filter, if it now works you need to examine the new primary filter and associated seals and gaskets.

-If putting on the old primary does not solve the problem then move on to reinstalling the old secondary and see what happens.

-It's possible there is nothing wrong with your new filters, a pinhole leak is all it takes to suck air into the system without showing any signs of fuel leaking out of it.

-All of the above is dependent on properly bleeding the system before trying to start the engine otherwise all you are doing is introducing air into the injection pump and lines to the injectors which will only further complicate narrowing down the problem.

-Myself I would go through the system step by step verifying good flow at each point until I had a good flow feeding the injection pump before even trying to start it again.

Follow Diesel Tech's advice. The fuel flows from primary filter through supply pump and then to secondary filter. So, see if fuel is going through and I has to be hand pumped, not gravity flow.