Fuel Starvation

[Jon Green]

Hi Guy's,

 

I'm having a problem with a misfire which starts about 4-5 miles after starting the car and progressively gets worse. I'm running a 2.1 pinto with twin 40's and the standard electronic ignition modual. I've been round the ignition checking for problems and cleaned the carbs through a few times with no improvement... in fact it seems to be getting more servere.

 

Wednesday night a few of us South Lakes Hoodies met up and they suggested that my standard mechanical fuel pump would be struggling to keep up with my demands and that it all sounded like fuel starvation causing the misfire.

 

As chance would have it one of their associates had a facet solid state fuel pump on their garage shelf that had been fitted to something for a very short period and could probably be persuaded to part with it for a small fee.

 

Im now looking for the best place to put the pump. Favourite place at the moment is under the rear diff mounting bracket just in front of my full width RH stainless fuel tank.

 

The question I'm eventually getting round to is:

 

1. Where have other 2b owners fitted theirs; and

'

2. Do you need to use a pressure regulator with twin dellorto carbs or is it fine to have the max. pump pressure of 5bar ~ approx.;

 

3. And finally... is there anything else I should be checking....some other possible source of the misfire?

 

 

Cheers,

 

Jon

[Longboarder]

Instant thought is partial vacuum in the tank. When you next get the miss, stop and whip of the fuel filler cap. If there is a suck of air you need a vent. Drill a tiny hole through the cap anyway? Thats what I did.

The mechanical pump in reasonable working order is fine for supplying twin forties.

Dont faff with fitting an electric one. It would need a pressure limiter. Fit a new machanical one if you're sure the present ones duff.

 

Nigel

[Guest salty_monk]

Mechanical's are only about 12 quid from a factor....

 

Make sure there's no "crap" in your fuel lines...

[Guest chris brown]

Make sure there's no "crap" in your fuel lines...

My first thought also try blowing them through from back to the front not blowing from pump to tank as if there is any crud in the line you will put it back in the tank. What state is the inline filter? As Nigel says the mechanical pump should have no problem in supplying twin forties even on the track so road use should never be a problem.

[Grim]

i've got an almost new mechanical fuel pump spare, if you want one for next to nothing

[Longboarder]

Tank crud is likely to be either a constant problem if its got into the fuel lines or random. Jon's problem is predictable after five miles.

(Sods law. He'll probably find it's the coil or something non petrol related )

 

Nigel

[Guest Simon cooper]

Did you say 5 Bar????????

If you did, that pump is off a fuel injected system and will blow every seal, pipe, joint and splash about 3 pints a minute all over your engine bay and floor.

Have you got a fuel return on the car? if you have, block it off.

Have you got a fuel filter in line? Change it.

Check delivery at the carbs. 1/2 a pint in 30 seconds is plenty. If you drink it faster than that, you have a "Real " consumption problem.

Dellorto's are happy with about 3.5psi (Which is about .25 Bar)

Mechanical pump is fine and does not need regulating or a return when used on side draughts.

I have had 48 DCOE's running off a pinto pump on a 2.1 pinto with no probs at all.

Regards

Simon

[Jon Green]

Woops.... yes that should have been 5 psi..... not bar!

 

No i don't have a return pipe to the tank..

 

I'm about to go into the garage and change the in line filter and give it another blast to see if its any better. I'll check the flow too.

 

As i have already got the electric pump, is it a recommended upgrade to change it from the mechanical one or is it a waste of time?

 

I'll let you know how it goes!

 

Cheers,

 

Jon

[Jon Green]

Ok, just come in from the garage....

 

 

I disconnected the fuel pipe from the carbs and ran the starter motor of 30 seconds. I collected more than 1/2 a pint of fuel so i don't think that i have a fuel starvation problem. I have found that the plastic in-line filter in the engine bay has been installed the wrong way around. Might this effect anything? Im going to buy a new one rather than turn the old one around.

 

 

Anymore ideas?

[Guest salty_monk]

Filter - probably not, worth a try though. Did you break the pipe before the filter when you did your test then?? I would try new module, rotor, cap, plugs & leads to be on the safe side if I was you, swap with someone's good known ones on stuff like coil & leads if you don't want to splash out.... when things get warm (like after 5 miles...) problems can crop up that aren't there when it's cold....

 

If swapping those doesn't work then take a look at your wiring down to the coil.

 

Dan

[Jon Green]

Dan,

 

I took the fuel pipe of the carbs and put it into a container. The fuel measured came through the filter on its way from the tank.

 

I recon the only reason that they have a flow direction is so that the muck it catches can be seen on the outside of the filter material. Mine will all be trapped inside! That'll be why it looks like new!

 

Think i'll strip my coil / dissy / module wiring and start again just to be on the safe side. I can make it nice and tidy this time!

 

Thanks for the advise.

 

Fortunately my dad wants a fuel pump for his scimitar anyway!

[Dave R]

not that i think its your problem, but i had one of those clear plastic filters... i had managed to put a twist in the pipe fitting it, it managed to almost clse the pipe off

took me a while to find

[Jon Green]

Just a quick update! Solved the problem..... I took the ignition off the car including all the wiring and dissy and put it back again. Changed the inline plastic fuel filter and cleaned out the banjo filters each of the dellorto's.

 

All seams to be running fine now.... better than it has ever before to be truthful!

 

Thanks for the help

[Guest salty_monk]

Good stuff. Glad you're back on the road. Dan