DX chokes and is not able to start

Hello,
I'd appreciate help with troubleshooting of my '83 Golf GTI.
Recently my Golf had fuel tank and fuel pump replaced. The tank is a second hand diesel tank, the pump is Mitron. The car run well for 80 miles, but after that started to choke even during moderate acceleration. I returned home hopefully but I was not able to restart the car when it was still hot (no single ignition). When I was trying to start the engine when it cooled down it restarted for 2-3 seconds and cut. Per Haynes manual I measured fuel flow at fuel distributor return hose putting a switch instead of fuel pump relay. The flow was 700 ccm/30 seconds while Heynes specifies minimum at 900ccm/30sec, so this pointed a problem with fuel supply. I measured current at fuel pump relay socket -  it was 7.75A, so above nominal 6.5A suggesting fuel line is clogged somewhere. I also did a painful job of cleaning fuel pickup through fuel level measuring unit opening at top of the tank. The pickup was badly clogged however after the cleaning operation the fuel flow remained the same (700ccm/30 sec). Now I see two possible reasons of the problem:
1. Fuel pressure accumulator limits the flow resulting also in increased fuel pump current (7.75A).
2. The Mitron pump quality is really poor (because of cost I have not decided to buy Bosch) and the pump is worn after 80 miles not being able to provide enough pressure/flow. Also the pump might have worse efficiency than Bosch and thus current consumption is 7.75A, not 6.5A.

Please advise before I take a risky move of disconnecting fuel hose from pressure accumulator to measure fuel flow just after the pump. I called it risky since the accumulator/hoses look so corroded that I may easily break something trying to disconnect them.

Thanks.
Makavity

just a few stupid questions,

did you check for gooey stuff in:
fuel filter
pressure regulator (in fuel distributor)
check the pickup again for more ick?

stuporman

hi

have you checked the ignition side of things ?
disconnecting at the accum to check flow rates , wont  make any difference its just a pressure vessul after all
im also thinking is the diesel tank the same design as the fuel injection ? does it have a pot at the bottom & pick up point in the centre.
baz

My money is on the fuel filter....

Let me clarify on those things you pointed:

1."have you checked the ignition side of things ?"
No, because:

• • • Fuel flow is too low what points a problem with fuel system
    • Engine is able to cold start for 2-3 secs, what also suggests ignition is ok

2. "disconnecting at the accum to check flow rates , wont make any difference its just a pressure vessul after all"
This is what Haynes suggests. Is there any backflow valve in the accumulator which might get stuck? Or rust debris could clog the accumulator?

3."im also thinking is the diesel tank the same design as the fuel injection ? does it have a pot at the bottom & pick up point in the centre."
Diesel tank is exactly the same including pickup/pot. The only difference is pickup filter mesh size - gasoline one is much finer. Also, the car run well for 80 miles after tank replacement.

4. "did you check for gooey stuff in:
fuel filter
pressure regulator (in fuel distributor)
check the pickup again for more ick? "

• Fuel filter has been replaced just after fuel tank replacement.
• I haven't touched pressure regulator (in fuel distributor), since it should be protected by fuel  filter.
• I haven't checked the pickup after cleaning again, since I took fuel flow measurements just after the cleaning, the tank looked pretty clean, so I do not believe it may get clogged so quickly again.

For purpose of further troubleshooting let me quickly summarize the story:
1. The car choked during acceleration and cannot be hot/cold started shortly after that.
2. It run well after fuel tank, pump and filter replacement for 80 miles. The current pump is brand new Mitron, however I could not confirm this vendor reputation searching over the net.
3. Fuel flow measured at fuel distributor return hose is 700ccm/30 sec what is below specification minimum which is 900ccm/30sec (Haynes).
4. Current measured at fuel pump relay socket is 7.75A vs suggested by Haynes nominal current=6.5A.

Thanks for feedback. Please advice.

"Makavity" said

Let me clarify on those things you pointed:

1."have you checked the ignition side of things ?"
No, because:

• • • Fuel flow is too low what points a problem with fuel system
    • Engine is able to cold start for 2-3 secs, what also suggests ignition is ok

Hi
Ok i do see your point , but for all the time it takes , i would be checking it

2. "disconnecting at the accum to check flow rates , wont make any difference its just a pressure vessul after all"
This is what Haynes suggests. Is there any backflow valve in the accumulator which might get stuck? Or rust debris could clog the accumulator?

You would need some serious amount of s**t to block the accum.from memory the inlet & oulet are basically plumbed into the vessel space with the mechanical part that maintans pressure at the back of the vessel .
there is also a non-return valve after the fuel pump to stop a loss of pressure back to the tank, Have you fitted this non-return-valve ?

"You would need some serious amount of s**t to block the accum.from memory the inlet & oulet are basically plumbed into the vessel space with the mechanical part that maintans pressure at the back of the vessel ."
Yeah, my perception it the same. But still Haynes suggests searching the reason of high fuel pump current in the accumulator or lines.

"there is also a non-return valve after the fuel pump to stop a loss of pressure back to the tank, Have you fitted this non-return-valve ?"

I do not have any separate non-return-valve. I think there is one integral with the pump.

My intuition tells me problem is in the pump (but this means brand new pump deteriorated over 80 miles). However before investing money in new one I would like to clarify what is the reason for high fuel pump current (7.75A vs 6.5A). Assuming quick pump deterioration (clearances increase due to rotor-stator wear) the current should go down.

Hi
the non-return should be built into the banjo connection that screws into the fuel pump , is this what you have got ?
baz

"the non-return should be built into the banjo connection that screws into the fuel pump , is this what you have got ? "

Yes.

M.

i would replace the filter again as its cheap and easy. unless the tank was completly spotless some diesel might have still been in there which would have been caught mby the filter. i agree though i wouldnt be happy with a pattern fuel pump, so a bosch one would be on my list of things to buy

I have also had a similar issue as yours caused by a faulty non-return valve. these unscrew from the engine side end of the pump (at least on bosch pumps)

The story becomes interesting. I've just completed next test:
I disconnected fuel line just after the pump and measured fuel flow and current (I realized I have another banjo connector I can use for the test so I avoided disconnecting the line at the accumulator).
The flow increased twice to 1400ccm/30sec, current consumption dropped significantly to 2.7 A (same parameters measured at fuel return line at fuel distributor were 700ccm/30sec and 7.75A). So, looks like the pump is ok. My next check will be taking same parameters aft and prior to fuel filter. But still, it's difficult to imagine brand new filter clogged over 80 miles. Before any debris can stuck in fuel filter it should go through fuel tank pickup filter (this one in diesel is rough so I can imagine that) and fuel pump built-in filter which is much finer. If the fuel filter is causing my problem the only scenario I could imagine is that gasoline solved some fraction of diesel fuel residues in the tank (I installed a tank from diesel Golf) and then they flowed through the lines, accumulated in the fuel filter and clogged it.

Also, the test above takes off suspicions from non-return-valve in the pump (which is new anyway since it came with new pump).

daft question what fuel does your car use?

I disconnected fuel line at fuel filter outlet and to my surprise I found non-return-valve in the fuel filter outlet banjo connection bolt clogged with amber color, jelly chips (up to 5 mm lenght, 2mm width). After the valve rough cleaning I measured fuel flow at the fuel filter outlet. Fuel flow was 1350ccm/30sek, current consumption 3.75A - so both parameters quite fair. Finding those chips at fuel filter outlet means they might be everywhere in fuel injection system: fuel distributor, injectors, etc. Does anyone know how to fight that ? Kerosene might by solving the chips if they come from diesel fuel fraction,  but I'm not sure if using kerosene would be safe for the injection systems (seals, etc.). The sneaking question is how those chips appeared aft to the fuel filter and what their origin is?

Answering Nighthawk question: my car uses unleaded 95 octane gasoline from Neste. Confusion may come from the fact that I was so airy to install second hand tank from diesel Golf.

"The only difference is pickup filter mesh size - gasoline one is much finer. Also, the car run well for 80 miles after tank replacement. "

hi
sounds like you might need to soures the petrol filter for the tank pot  then maybe inspect it in a few weeks again.
That chips your talking about could be the material VW seem to have used inside the Pot in the tank ( i know mine was flaking slightly & clogging my non-return-valve  sticking it open ) i had to clean my non-return twice & the car has run A1 since.
Also i am running non-supermarket fuel & moslty 98 octane I had lots of hot-starting probs before running on supermarket fuel  :dontknow:
baz

if you're lucky the banjo bolt on the metering head has a mesh screen inside it which will have caught some of this stuff

with regards to the tank was it cleaned out thoroughly as it was a desil take if there were any traces of desiel in the tank if this has gone through the system could have caused other problems

also if you dont want to use kerosene in case of damage the only option you have to check is to take apart the fuel system and check it piece by peice and flush it all through to make sure all traces are out of the system

1. I cleaned the non-return-valve at filter outlet banjo connection but it did not solve the problem. Fuel flow measured at distributor outlet is still too low (~600ccm/30sec) and fuel pump current too high (7.7A). I have not tried to start the engine but I do not expect this to be successful when fuel flow is still so low.
2. I did more detailed inspection of the fuel filter and my conclusion is that debris which clogged my injection system come from fuel filter sealing (around the bottom).This is amazing since I fitted brand new filter. The filter is from Italian manufacturer Clean Filters - be careful using those.
3. Looks like what I should do is to dismantle injection system and clean it. I will start from pressure regulating valve, then remove plunger and disconnect injectors from the fuel lines. As I found out particular injector port valves in the distributor are not accessible and cannot be cleaned - is that correct?

yeah you cant really get to the injector ports to clean them, you might have luck splitting the metering head in half to clean it all out but do this very carefully and only as a last resort