Fuel starvation issues Electric and mechanical pump

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sallmark
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Fuel starvation issues Electric and mechanical pump

Post by sallmark »

Hi 8090, I'm a bit stumped and really need some friendly advice before i start to cry!

I have 1986 1.9DG transporter that I have been converting into a camper for some time. I have had it on the road for some time and a few months ago the fuel stopped getting into the carb and I broke down, did some fiddling and got it back some how just before the RAC man arrived and he suggested that it might be the fuel pump. so I replaced the mechanical fuel pump and all seemed fine until it did the same thing again. hummm. Then tried a new an electric fuel pump and it seemed to struggle getting up to pressure. I then looked on the various forums and suggested that it could be a blocked fuel tank or line and as I want to replace the tank as I could smell fuel if I over filled the tank thought this might be a good idea.

So replaced the fuel tank and the pipes but not the hard line, as well as float valve and seals.

After all this I then thought I would just try the old Mechanical pump and see if that would work which it did for a day but then the Engine started to race fast and faster as it got hot. I then let it cool down when I got home and when it started again it stopped pumping fuel. So switched back to using the new electric fuel pump with regulator but its really struggling to get enough fuel pressure. I have no pressure measuring device but have a clear fuel filter before the it goes into carb and its trickling through rather than filling up which doesn't seem right.

the only thing I haven’t replaced is anything to do with the carb, except had previously replaced the choke pull down unit, and not changed anything on the return side to the tank, including the none return valve. Could this be the issue?

what could be causing low pressure from the pump. got to be a blockage?? I have some pressure when idle but not under load, get about ten yards down the road and it conks out until it gets fuel back in the carb.

Could fuel pipe size be causing an issue, I'm coming of the 8mm connections form the pump up the original hard lines which don't appear to be blocked?

Im using this electric pump,
http://www.carbuildersolutions.com/uk/e ... ump-silver" onclick="window.open(this.href);return false;
connected directly to the battery with a relay connected to the ignition coil and i'm getting 12V when idle.

I have a fuel regulator inline which is recommended with electric pumps it does seem to effect the pressure but only a tiny trickle. I'm going to take off the regulator to see what that does just to eliminate from the equation.

So just to be clear I have
Fuel tank connected to Fuel pump next to tank, then up the hard line to a regulator then to a fuel filter then out to the carb.

Could there be a problem with the carb that is causing these issues?
The Tank is new could I have an issue with some of the lines to the expansion tank which would cause a pressure a leek(clutching at straws here people)

Sorry for my dyslexic ramble hope someone can decode my many issues. Any ideas or things to try would be appreciated.

cheers

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marlinowner
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Re: Fuel starvation issues Electric and mechanical pump

Post by marlinowner »

There's a cone shaped filter inside the carb inlet pipe, this could well be blocked. There's details in the wiki.
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T25Convert
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Re: Fuel starvation issues Electric and mechanical pump

Post by T25Convert »

Hi,

As above, first check all filters, including the nasty little cone one in the carb inlet.

Early in your post you suggest you have replaced the 'float valve' and seals, but later you suggest you haven't done anything to the carb. By float valve do you mean the fuel gauge sender which goes into the petrol tank?

If you do, it may well be that your float valve in the carb is stuck. You may or may not be aware that when the fuel enters the carb it goes through a small valve controlled by a float - this allows the correct amount of fuel in so that the carb doesn't overflow. However, these can get stuck so that the valve doesn't respond to the movement of the float.

If either the valve is stuck, or the filter is blocked, you won't see a good flow of fuel through your clear filter as it has no where to go, so you'd only get a trickle....

Quick test before you start poking around in the carb, whip the fuel hose off the carb and stick it in a glass jar, turn the electric pump on and see if you get a good flow. If you do then the problem is in the carb.

Good luck!

Cheers,

Alex
RIP - George - 1.9DG '85 AutoSleeper Trident - rusted away

George Second - 1.9DG '89 Caravelle

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ermie571
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Re: Fuel starvation issues Electric and mechanical pump

Post by ermie571 »

A good cry often helps.


Or a medium sized branch!


Em
xx

:ok
2.1 DJ 1990 Caravelle (died and gone to heaven)
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sallmark
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Re: Fuel starvation issues Electric and mechanical pump

Post by sallmark »

Thanks for the response, I had looked at that filter the first time I broke down to see if that was the issue but is was clean as far as I could tell.

When I said float valve i meant the gravity valve that sits on top of the expansion tanks. didn't touch the carbs and don't want to just yet. But your advice on a possible sticking float valve might be one to explore.

I had some luck last night increasing the pressure by removing the fuel regulator and it seemed fine for a while. did some load speed driving around the neighbourhood and up some small hills and it looked ok. Thought I would test it at speed and took it down a fast A road and it started to cut out when i drove over 40mph ish.

I have the feed from the relay connected to the coil. I'm wondering if this might be an issue, if the voltage is dropping under speed then this might be switching the relay off and thus the pump off. I'm going to try connecting the relay to the starter motor instead and see if that brings me any joy.

any advice on cleaning float valve in carburettor and or lubrication that I could put on the Carburettor to help eliminate anything from sticking.

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Re: Fuel starvation issues Electric and mechanical pump

Post by ghost123uk »

sallmark wrote:I have a clear fuel filter before the it goes into carb and its trickling through rather than filling up which doesn't seem right.

Note re that ^^^. This is normal. OK, if you had the fuel filter mounted upright, with the feed at the bottom and the take off to the tank at the top, yes, it would fill right up until it was full and then feed into the pipe at the top, to the carb. But our filters are mounted on their sides. This means that fuel starts to go into the filter, but as soon as it reaches about half way up, it starts to flow into the feed to the carb pipe. Then there is air trapped in the top half of the filter that has nowhere to go = not a problem. Some folks "prime" their horizontal filters so that they are full of petrol before fitting them to prevent this. Anyway, because of the way / position our inline near the tank filters are, that is not so easy. I don't prime them as I don't see it as a problem except that to be fair it results in less actual "filter area" but I have never had an issue because of that.
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Re: Fuel starvation issues Electric and mechanical pump

Post by ghost123uk »

My money is on 10:1 that this is a simple blockage. Take the feed pipe off the carb and put it into a clear pop bottle. Fire the engine up (it will run for a minute or two off the fuel in the float chamber) and note how "healthy" the squirting of fuel out of the pipe is. It should be a good old stream, not a dribble or not intermittent.
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Re: Fuel starvation issues Electric and mechanical pump

Post by ghost123uk »

All this back to back posting of mine :roll:

sallmark wrote:Thanks for the response, I had looked at that filter the first time I broke down to see if that was the issue but is was clean as far as I could tell.

Just to confirm, that is the tiny cone filter in the carb's inlet pipe you looked at, yes ?

sallmark wrote:didn't touch the carbs and don't want to just yet.

Standard DG only has one carb. Does yours have two ?


sallmark wrote:I had some luck last night increasing the pressure by removing the fuel regulator and it seemed fine for a while.

Points to a blockage

sallmark wrote:I have the feed from the relay connected to the coil. I'm wondering if this might be an issue, if the voltage is dropping under speed then this might be switching the relay off and thus the pump off.

The voltage won't be dropping off at speed. The voltage at the coil is (98%) independent of speed or load.

sallmark wrote:any advice on cleaning float valve in carburettor and or lubrication that I could put on the Carburettor to help eliminate anything from sticking.

That is unlikely to fix your problem. Best identify exactly what is going wrong rather than trying "this and that". Anyway, a sticking float valve would also not be speed dependant. A blockage is though, as more fuel needs to flow at higher loads / speeds (sorry, I know you knew that !)
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Re: Fuel starvation issues Electric and mechanical pump

Post by AdrianC »

sallmark wrote:I had some luck last night increasing the pressure by removing the fuel regulator and it seemed fine for a while. did some load speed driving around the neighbourhood and up some small hills and it looked ok. Thought I would test it at speed and took it down a fast A road and it started to cut out when i drove over 40mph ish.

What pressure is the pump delivering? (Or, rather, what pressure is it specced to deliver?)

Carbs want about 5psi/half bar. If it's an injection "universal" pump, that'd typically be delivering 35psi/2.5bar or more.

Have you tried taking the pipe off the carb inlet, and seen if there's actually fuel being delivered to the carb in any kind of sensible quantity?
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Re: Fuel starvation issues Electric and mechanical pump

Post by ghost123uk »

AdrianC wrote: Have you tried taking the pipe off the carb inlet, and seen if there's actually fuel being delivered to the carb in any kind of sensible quantity?

Agreed :ok That is the next thing to do.

ghost123uk wrote:Take the feed pipe off the carb and put it into a clear pop bottle. Fire the engine up (it will run for a minute or two off the fuel in the float chamber) and note how "healthy" the squirting of fuel out of the pipe is. It should be a good old stream, not a dribble or not intermittent.

:wink:
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sallmark
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Re: Fuel starvation issues Electric and mechanical pump

Post by sallmark »

Thanks for all you help and support! It took a while but final found the culprit, The New filter from JK was for sum reason blocking the flow.

Checked fuel flow from Pump and then through the lines and was fine then through the filter and it became a trickle. I think the pump was either reducing pressure when it hit the filter of the filter was faulty/wrong.

I filmed my fun so will try and send up some videos to show you all what i did to solve issue. Strange one though.

Got a Fuel pressure gauge and set the regulator to the correct pressure according to book!

Now have another issues might be related but I think for another thread.

Having never done any mechanics until about 2 years ago, I have been able to do so much work on my van with the help and support of Club 8090. I don't post often as it takes me ages but I have been so thankful for all your advice.

Cheers
Simon

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