Well after getting the truck started and pulled into my bay, I noticed the engine ran kind of rough and has VERY slow acceleration, I flipped on the high idle switch and it SLOWLY went into high idle, the engine just doesn't run right. I decided to check a lot of the basics, air filter, oil, fuel tank, I ended up changing our the main filter and fuel water separator-no change but what was even stranger was when I went to unbolt the bleeder on the side of the housing to bleed the air, I was getting no fuel? Went to unhook the main feed line to the separator and no fuel? But this truck is running? Very strange, the primer button felt like it collapsed as well and had no pressure. I may end up putting compressed air into the lines to try and see if there is a blockage but was curious if someone has seen this before?
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M1083a1p2 No fuel flow through fuel water separator?
- Thread starter polk738
- Start date
Ronmar
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- Port angeles wa
no fuel at the primary probably means it is sucking air instead of fuel.
1. check the primer is pulling suction. disconnect the input fuel line at the primer, put your finger over the inlet fitting to the primer to seal it. push in on the primer it should stay in as long as you hold a seal on the inlet with your finger tip.
if it does not stay in, remove the filter, disconnect the outlet line and unbolt the primer assembly from the side of the engine, and flip it upside down. there is a flapper type bypass valve that is probably not sealing which is usually why the primer cannot pull a vacuum.
If the primer seals and the bulb stays in with your finger over the inlet, and it won't lift fuel from the tank, the lift line probably has a pinhole in it somewhere sucking air instead of lifting fuel... It takes a surprisingly small air leak to jack this fuel system all up... Working primer and sealed line with no fuel init, you should be able to lift fuel from the tank to the primer(feel and hear fuel in the primer button) in 16 pumps. You can also pump primary fuel pressure up to ~10 PSI fairly easily with the primer once all the air is out of the system(bulb becomes more difficult to push as you get all the air out and start to force fuel hydraulically past the primary pressure regulator at the back end of the cylinder head)
I did a Youtube video showing the primer bypass flapper clean and inspect not long ago as this is not an uncommon issue. but the primer not lifting does not explain your running issue, a vacuum leak on the lift line somewhere could explain the running issue also... A pressure gauge looking at primary fuel pressure(output of HEUI lift pump/input to main fuel filter) would also show an air leak pretty clearly(I have a video on that also
...
On Youtube look for my user name Rronmar (2 R's in front) to see my vids on the LMTV. Mine is a 3116, but the fuel feed is basically the same between 3116/3126/C7 engines...
1. check the primer is pulling suction. disconnect the input fuel line at the primer, put your finger over the inlet fitting to the primer to seal it. push in on the primer it should stay in as long as you hold a seal on the inlet with your finger tip.
if it does not stay in, remove the filter, disconnect the outlet line and unbolt the primer assembly from the side of the engine, and flip it upside down. there is a flapper type bypass valve that is probably not sealing which is usually why the primer cannot pull a vacuum.
If the primer seals and the bulb stays in with your finger over the inlet, and it won't lift fuel from the tank, the lift line probably has a pinhole in it somewhere sucking air instead of lifting fuel... It takes a surprisingly small air leak to jack this fuel system all up... Working primer and sealed line with no fuel init, you should be able to lift fuel from the tank to the primer(feel and hear fuel in the primer button) in 16 pumps. You can also pump primary fuel pressure up to ~10 PSI fairly easily with the primer once all the air is out of the system(bulb becomes more difficult to push as you get all the air out and start to force fuel hydraulically past the primary pressure regulator at the back end of the cylinder head)
I did a Youtube video showing the primer bypass flapper clean and inspect not long ago as this is not an uncommon issue. but the primer not lifting does not explain your running issue, a vacuum leak on the lift line somewhere could explain the running issue also... A pressure gauge looking at primary fuel pressure(output of HEUI lift pump/input to main fuel filter) would also show an air leak pretty clearly(I have a video on that also
...On Youtube look for my user name Rronmar (2 R's in front) to see my vids on the LMTV. Mine is a 3116, but the fuel feed is basically the same between 3116/3126/C7 engines...
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