1.6 NA return fuel line issue

[jseeley]

I'll try to make my story as short and informative as I can. I've had my 85 1.6 NA Diesel for a little over a year. The injector pump had begun to become leaky (probably from all the ULSD) I sent my IP out to Giles at Performance Diesel for a rebuild (Performance Pump) After getting the pump back on, new timing belt (and v-belts) everything fired up and seemed good to go. At that time I didn't have a timing dial but the car was running decently. However after taking it for a spin within a few miles it stalled and I couldn't get it restarted. Looking over everything it turned out the belt had jumped time at the IP sprocket... near catastrophe there. Everything was tightened back up, and belt timing reset. The car would start and idle roughly, but would not respond to throttle. After that I waited for a timing dial to arrive. Once I had a dial I measured the timing at .87 (retarded) Adjusted the pump to .97, which is the high end of spec for an '85. Started it up, ran decently at first, then had the same behavior, rough idle, no throttle response. After lots of troubleshooting I found the car would run normally when fuel return was run into a jar, but not when it was hooked up to the main return line. So, is my main return line blocked? Fuel tank vent issue? Leak in return line? My current plan is to replace the fuel return line... but suggestions, comments questions are all welcome... I am a NOVICE at this.

Also where do I even get a new return fuel line for a diesel? My "hard" lines do not appear to be metal, they're hard plastic.

[8v-of-fury]

You could try blowing through the line with low pressure shop air.. 30-40 psi.. may just be gunk in the tank..?

if the fuel can't get out of the pump and back to the tank, new fuel can't get in either and stall.

goodluck

[8v-of-fury]

P.S WELCOME TO THE BEST DIESEL BOARD IN NORTH AMERICA

You'll learn lots of gooood stuff here !

[jseeley]

Thanks; I've been lurking forever  

I only got to drive with My Giles pump for a few miles.... I'm REALLY looking forward to getting everything sorted out so I can drive it again... this is my daily and its been down for almost 2 months.

Just to confirm; A leak in the return line wouldn't cause this issue right? Only a blockage? I looked for a leak but I couldn't find one, my trusty Bentley sent me down the path of a return line issue, listing a fuel line return leak as a possible cause of my symptoms... A blockage may be easier to identify than a leak which is why I was considering just replacing the return line, but I dunno where to get one.

To throw this out there; What is everyone's opinion of the water separator by the fuel tank? Should I delete it while I'm down there?

[rabbitman]

Most mk2 people take the water separator out.

A leaky return line will only waste fuel but won't effect the running at all.

A blocked return line will cause VERY high internal pump pressure thus causing way excessive dynamic timing advance and also most likely cause leaks in the pump.

Air leaking into the feed line will make it run bad, you can see that if it has a clear line.

[Dakotakid]

That car looks tastefully good, dooode!

[jseeley]

Most mk2 people take the water separator out.

A leaky return line will only waste fuel but won't effect the running at all.

A blocked return line will cause VERY high internal pump pressure thus causing way excessive dynamic timing advance and also most likely cause leaks in the pump.

Air leaking into the feed line will make it run bad, you can see that if it has a clear line.

I ran some clear lines during troubleshooting; The send from the tank and return out of the pump are good once it's primed (no air bubbles) All of the engine bay lines are switched to Viton lines now though. I wonder if a clog in the return was the demise of my original pump before getting a rebuild... I'll try to clean out my current return line if I can... otherwise replace it. If anyone knows were to get a new return line please let me know. Is the line specific to MK2 diesels? Seems like just hard plastic tubing, can I get it at a regular auto supply shop? I'm going to check a scrap yard and VW parts supplier tomorrow. Feels good to be getting to the bottom of all my issues. 

[theman53]

I am with Dakotakid on the looks. It is awesome. Please get me the color code as that is the same as my jetta I believe and even if it is not it is close enough for me to do it over without the inside not matching or being off.
Good luck on the lines, I ran the viton stuff to original.

[jseeley]

I am with Dakotakid on the looks. It is awesome. Please get me the color code as that is the same as my jetta I believe and even if it is not it is close enough for me to do it over without the inside not matching or being off.
Good luck on the lines, I ran the viton stuff to original.

I WISH I knew the color code myself; The car was re-painted by the previous owner. I eventually want to re-paint it (there are some dings and areas that need attention) and I really want to keep the same color. The original color of the car was Blue Metallic (LA5Z) which is a lighter blue than it is currently. Right now I'm thinking its "Techno Blue" LW5Y which is a New Beetle color... I'll have to find one someday and park next to it to confirm.....  

Thanks for all the compliments!

[Dakotakid]

Just take a knife and scratch some of it off and take it to the paint store for evaluation.....

(Pull the fuel door and have it evaluated at the paint store).
My 16 valver would look good with those clothes!

[jseeley]

Got some advice that it could be the check valves in the return line that are clogged. I'm tearing into it tomorrow, are the check valves needed, should I replace them? Procedure for cleaning them? Remove it completely?

[jseeley]

I checked the hardlines; They are clear, no clogs or leaks. I replaced all the rubber connecting lines with new viton lines, both by the tank and in the bay. The check valve on the return line seems failed, fuel flowed in either direction freely so I removed it for now. The check valve on the supply side seemed good though. I also deleted my water separator by the tank to rule out any air leaks or clogs there and still same symptoms on my vehicle. Start but idles roughly and eventually stalls. I can run it perfect from a jar of fuel, and actually even run it with the supply from the tank and the return to a jar, but when I hook up the main return if eventually will stall. Right now I'm noticing 2 things. The return line does not seems to put out a whole lot of fuel, and under heavy throttle it actually seems to suck fuel in, not sure what that means....  Also my stop solenoid is leaking fuel on the pump, which is distressing since it a freshly rebuilt pump from Giles pump and the car only has run about 1.5miles since its all back together. Anyone have any ideas whats happening? I pulled the sending unit from the tanks and its good as well, no clogs. I'm very sure everything is primed as i've been doing it all with a hand pump and clear lines till there are no more air bubbles.

opinions welcome!

[burn_your_money]

Is the OUT bolt stamped out?

There is a filter in the out bolt, make sure it isn't clogged up.

Where is the stop solenoid leaking from?

[jseeley]

Is the OUT bolt stamped out?

There is a filter in the out bolt, make sure it isn't clogged up.

Where is the stop solenoid leaking from?

I had the return banjo fitting apart to check, seemed ok. Stop solenoid is leaking from the very top were the screw goes in to hold electrical connection from the ignition; Lower part where the solenoid screws to the pump seems ok.

[jseeley]

Giles thinks it's a restriction at the supply check valve; Anyone know where to get a comparable replacement? The part number I had above are for a mk4 I think... REALLY hope this is my issue...

The whole thing with the injection pump pulling fuel from the return side is throwing me though... is this the expected behavior if the supply side is restricted? I suppose I could test with 2 bottles of fuel, one for supply and one for return to ensure the pump if functioning 100%. It runs well from a single bottle, but I couldn't tell if the return was pulling fuel or not then....