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General Information => Troubleshooting => Topic started by: Ohiobenz on June 27, 2021, 10:54:15 pm
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Driving on hwy 65 mpg all of a sudden it just quit... coasted to the side and it idled fine but won't go above 1500 rpm. Stopped and put a clear inline fuel filter on - it's not getting all the way full.
Managed to limp almost home on back roads, had to call a tow truck for the last 2 miles :-(
Dropped the fuel tank (88 Samurai) but there is no screen on the pickup tube. All the lines are tight and clear.
I'll be working my forwards to look for any leaking lines tomorrow.
Could something have let loose in the IP?
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You may have a plugged fuel filter, the main one? Or are you only running a simple clear one between the pump and the IP. If that is the case you may have to pull the inlet side of the pump and look for something in there. The holes that feed the four injectors are very small and without a screen, on the tank or a good filter pre-pump, I would fear something in the IP that is blocking the flow through the main feed shaft, or secondary pump stage.
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There is a standard 85 Jetta fuel filter in the engine bay. I bypassed it with the clear filter so I could a) eliminate it as a cause/plugged and b) visually see the fuel flow.
The "clear" line into the IP is no longer clear lol.
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Replace the line with clear line going into and out of the pump.
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Air in the filter is a good sign.
Air doesn't go through a wet paper element easily.
If the filter is plugged the difference in pressure between the inlet and outlet is high enough to pull air through.
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The filter is on the suction side.
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No closer yet, but so far I've dropped the fuel tank to check for a pickup filter, dirt or water - none.
I've used my MiteVac and drawn fuel from the tank through the clear filter - no bubbles.
I've ran the engine (yes it starts and runs) out of a bottle in the engine bay through the clear filter so I could see flow.
I've run the engine out of the fuel tank through the clear filter, which is how I limped home yesterday...
I've run the engine through the Jetta filter, followed by the clear filter.
I've ran it up to 4krpm without load and without a stumble
I've run it up to 4krpm without load and up to 8psi boost without a stumble.
After all this, at idle, it all of a sudden stumbles like it's going to die, recovers, stumbles then idles smooth again.
I have videos of all of these different tests, but no longer have a photobucket account so no way to post on here.
What I see is a very low flow of fuel through the clear filter except right after a throttle blip.
Any recommendations on what to check now?
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Can you put a vacuum gauge between the IP and the filter? Sounds like you may have poor vane pump performance at Idle. Maybe some diesel purge to clean the IP out and see if that gets the vacuum up and drawing fuel like it is supposed to.
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Clear line coming from the pump
going back to the tank?
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Yup.
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See any air in it?
You say you dropped the tank and didn't see the filter?
Wait I keep forgetting you have a samuri could you put it in your sig?
Have you tried sending fuel backwards down the fuel line?
With a fuel pump.
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Updated signature.
I posted a list of what all tests I ran above.
Since I had a timing belt kit waiting for installation I opted to do that now, yanked the IP and shipped it to PDI yesterday.
Digesting the symptoms in my mind after the fact, it could have been an intermittent fuel shut off solenoid problem. The fact that it would run great, even under load, below 1500 rpm made no sense.
The fact that it would die at speed but then idle made no sense.
I had talked with Giles on Monday and he suggested trying 2 things: draw fuel out of a Jerry can on the floor, which it did successfully, and drive with a fuel can in the engine bay, which resulted in stalling after running well initially.
I've got 2 other vehicles and a dozen projects in the shop that I need to focus on instead of chasing my tail on this one.... PDI lead time is 3wks which allows me to complete a couple other things on the engine, and start building the spare tire carrier.
Hopefully Giles can/will tell me what he finds so that I can share it.
Due to the intended use of the Sammy in remote locations, I need the engine to be dependable, so spending the $$ on a Giles built IP is like an insurance policy lol.
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so spending the $$ on a Giles built IP is like an insurance policy lol.
Well you could look at like that but we all know that what you will get is a pump that will work very well and....
BRAGGING RIGHTS.
Giles pump!!!! top that one.
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Went back and looked at all the things you've done.
So that's a no you haven't tried backflushing the fuel system.
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True, not a back flush. If a little MityVac can pull fuel without any air bubbles, and there is no other filter or pickup screen in the system from engine bay to tank, what would a back flush accomplish?
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A little mityvac doesn't have near the flow created by an injection pump.
I was thinking since there is no screen in the tank
small pieces could go down the line and bridge up where there is a large to small transition in the line.
Something a mityvac could easily pull the small amount of fuel through.
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Ironically the MityVac pulled more fuel faster through the clear filter than the IP did. Maybe that just indicates that the vane pump was going bad.
I've found several other issues in the meanwhile and have the engine mostly torn down while waiting on the Giles pump to get built.