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Gt6 mk3 maiden voyage - break down....


Dolomitejohn
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Hi all. 

Maiden voyage today after 5 months of re commissioning...... After 2 miles it stuttered and cut out.  Would not restart unless I left it for 2 or 3 mins. 

Over the past few months I have been starting and driving the car around my road with no probs. However I did notice that after I flushed the tank and refitted I struggled to get fuel through. I blew through the fuel lines with compressed air. All OK. 

I also have a fuel filter just before the pump. 

When it stopped today the fuel filter was empty. Despite pressing the pump prime lever no fuel would come into the filter. 

However after leaving it for 5 to 10 mins the fuel filter seemed to fill itself to about a 3rd full.  Car then ran for about a mile. Repeat 3 times and managed to get home (with police escort)!  

All hoses replaced. 

I have noticed that the prime lever on the pump does not seem to be pumping. I used to hear it but now can't. 

I reckon fuel pump. 

Your thoughts? 

Cheers all. 

John 

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I dont like your comment about the filter being empty. Once fuel has come out of the tank to fill the filter I would think it'll stay filled even if the pump isnt working properly. I wonder if you havent got a lot of debris in the tank which may have come off the interior once you put it back into service and now is blocking the outlet pipe. When you leave it a while some of the debris dislodges and fuel can get through only to sucked back in again when the flow rate increases. Can you check the filter for dirt?  

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Check the tank breather is not blocked and a tank vacuum is pulling fuel back

The prime lever only works if the follower is on the back of the cam , if the engine always stops with the cam giving the pump a full stroke 

on the peak of the lobe the prime lever has no effect ,as its already pulled down on it spring,

   try turning the engine half a turn.

Other odd ideas  runs and stops can be coil 12v  polarity is reversed

Pete

 

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Have you had the top of the fuel pump off at any stage? It is possible to put the top back on slightly “out” (there is a tiny peg) which means that the pump sucks air rather than fuel. This usually means no fuel gets drawn at all, but if the leak is very slight it might explain your problem.

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Hi doug

How would you check the pump is working? 

I will remove the sender lid and shine a torch in to see what I can see.   I will also reverse blow through the pipe with the compressed air again. 

I am certain the tank is clean though. 

Just been out to see car again 5 hours after it last ran and the filter is now half full.  I guess it levels with the tank level? 

John 

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Pump check is easy enough, just disconnect the fuel line from the carbs and manually operate pump. You should get a good squirt of fuel into a container on each stroke however I dont think it'll be your problem as normally the pump just loses performance as the non return valves dont seal properly. This shows up as fuel starvation under high engine load so It would have to be very poor to not even pump enough to maintain a tickover. 

Now I think dirt is unlikely as well because you would have seen it in the filter but the other suggestions sound possibles...... 

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9 hours ago, dougbgt6 said:

a non floating washer getting sucked over the out let

Put it on the Forum a couple of years ago but I eventually found a piece of neutrally buoyant plastic in the tank, size of a 10p coin that caused similar symptoms you have; I had recently refueled.  The wait on the roadside provided time for it to float clear, drive, repeat.

Dick

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Hi dick

Going to remove float lid in a minute to see what I can see. 

I am also thinking that this car has been off road since 1999, so given the state of the rest of the engine rubbers I wouldn't be supprised if the pump was failing. 

Also thinking about it it stopped yesterday after I hit 60 mph so if the other forum post (sorry forgotten name) was right my return valve's may be faulty. 

If those don't solve the issue I will have to drain the 2 gallons in the tank and check the pipes. 

Thanks

John 

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I had a similar issue with my old GT6, the car was previously owned by a chap who used a fuel additive, somehow the foil covered disk had fallen into the tank. The car would tootle along fine for miles, the problem identified its self whenever I accelerated hard, the car would cut out and wouldn’t restart. I spent ages and a considerable amount of money replacing suspect parts and it still occurred. I eventually found the problem when in frustration after it had stopped yet again I removed the fuel pipe from under the tank - no fuel!

Left the car for a while and then drove it home and proceeded to drain the tank to inspect the inside. Couldn’t see anything and as the last last dregs were removed the silver disc slipped across the fuel pipe - removed the offending item and the car was fine thereafter. 

 

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John,

You said early in the thread that you'd tried pumping the hand prime lever, and that it "used to work" but doesn't now. Does it feel loose? I would expect to feel some spring load even if there's no fuel to pump (or a blockage pre-pump) or the valves are failed, but it would feel slack if there's a blockage post-pump or the pump is jammed in some way. I know Pete mentioned turning the engine over to ensure it's not on the cam but in my experience the prime lever normally has a longer stroke than the cam so you can still use it wherever the engine stops.

Fortunately the pumps are fairly easy to refurbish - I've done the one on my Vitesse twice (well, technically, I've done two different pumps that have, at different times, been on that car)

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When I press the prime lever it has spring resistance but does absolutely nothing to the fuel that has accumulated in the filter.  when I first got the car I could hear fuel being swished around when I pressed the prime lever.

I will take the pump off the engine and see what happens when I press the lever.(Will disconnect the fuel hose at carb).

Cheers

 

John

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John

I have now changed to a Huco electric pump, but did have various ‘experiences’ with the mechanical unit.

A few comments:-

It is not that unusual for a pre pump filter to be only partially full.

If using the priming lever you will only get the swishing sound if the float chambers on the carbs are empty.

Disconnecting the fuel supply at the carbs and a trial pump into a container as suggested, will confirm that the diaphragm and valves are functioning correctly.

Your original description said you had only run for 2-3 minutes, so I think fuel vaporisation can be discounted albeit the symptoms are not dissimilar. Had you run the car up to temperature before setting off perhaps?

My GT6 ‘failed to proceed’ on more than one occasion and would sometimes exhibit the filter emptying trick. On one occasion loosening the top of the fuel pump produced a satisfying hiss, presumably as a result of vapour pressure building up in the pump. Fuel could then be seen boiling in the base of the pump. Is it modern fuel.....who knows?

Ian

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I have also moved to a Huco pull pump mounted in the engine bay . The upgrade was for the same reasons ie unexplained fuel issues. Now you get the tick tick when the ignition is turned on and you know the fuel has reached the carbs 

Paul

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John

By modern, I meant the unleaded rubbish we are all sold now. A 'witches brew' by all accounts !

Your fuel was recent therefore assumed fresh, although we did definitely get a tank full of slightly dodgy stuff from the BP in Bude  on the RBRR. I think maybe the Super hangs around longer in garage tanks.

Will be interested to follow your investigations.

Ian

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Good to hear you've found the problem!

1 hour ago, Paul H said:

I have also moved to a Huco pull pump mounted in the engine bay . The upgrade was for the same reasons ie unexplained fuel issues.

I've recently converted my Vitesse back to mechanical pump because of unexplained fuel issues (often, but not always, with an empty filter) on the electric one I had. The OE mechanical pump on a Vitesse has a glass bowl so you can see clearly whether it's working! And, of course, you can see the fuel boiling in the pump after stopping the engine, which isn't unusual and has always happened - I remember commenting on it in a letter to the Courier back in 1989, when I had my first Vitesse.

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Hi all

OK dismantled the fue line, pump and also drained the tank again. 

Iots of rust particles came out of the tank. (think it's on borrowed time). 

Used compressor to blow out the pipes (steel pipe is in  2 sections as it has previously rusted in the middle). 

100 psi would not budge it.  Had to poke  screw driver in ends. 

Pump Also had rust bits on the clean side of inbuilt filter. Not sure how it got there.... 

Anyone got a good spare tank?? Or is there anything I can do to rescue my existing tank...? 

John

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My GT6 fuel tank produced lots of rust particles that caused carb issues ... then blocked the filter that I installed to catch the bits ...

I used the Frost petrol tank sealer kit. It’s a multi stage process to degrease, kill rust and then seal.

Particularly important is to ensure tank fully dry before adding the sealer... think I used the Mrs hair dryer for a few hours (on the tank not me).

Tank has to come out to do it all though.

That was 10 years ago ... and no problems since. So my experience good with this product.

https://www.frost.co.uk/auto-maintenance/automotive-tanks-products.html

Mike

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1 hour ago, Dolomitejohn said:

 

Anyone got a good spare tank?? Or is there anything I can do to rescue my existing tank...? 

 

If the tank is sound (ie not thinned or leaking) it can be cleaned out. 

Cheap way is to empty it of petrol take it out and wash it through, then chuck some nuts/bolts, or even bog bgravel in the tank, add some water and shake. Even better is strap it to a cement mixer (i am not joking!) and shake it about. This releases any flaky rust etc.

Then wash out thoroughly. Then some options. Just refit. Or a good dollop of phosphoric acid to "kill" any remaining rust. Or there are some tank sealer kits available, but you need to carefully follow the instructions. 

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11 minutes ago, clive said:

Or there are some tank sealer kits available, but you need to carefully follow the instructions. 

You really need to follow the instructions carefully and, as Mike said, dry it out really thoroughly. Otherwise the sealer will peel and float around and block your fuel outlet.

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That is why I have not used teh sealer, but instead rely on the phosphoric acid approach which hopefully leaves an inert surface. At least that is the hope.

Probably the worst thing is the car being left for extended periods. Regular use, and therefor fuel changes, seems healthy. After all, the tanks were always bare from the factory, though ethanol does absorb more water from the atmosphere (the E word is our equivalent of the B word, it seems to be the cause of all our woes)

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