Carb/fuel pump woes.

[manny]

I have just replaced the mechanical fuel pump on my HL1850 Auto as I thought the old pump was on its way out. I have also replaced the carb mounts with the club’s alloy mounts.
My replacement pump was very kindly gifted to me from the Club’s stand at the recent Triumph/ MG event. It was made clear to me that the history of the pump was unknown but it was believed to be good. The pump is branded “AC” and visually it looks identical to the old pump apart from the two halves of the body are pressed together as opposed to bolted.
Today I decided to tune the carburettor after fitting everything back on the car. I discounted the duel throttles, so they were independent, set the idle screws at 11/2 turns in and the mixture screws at two turns out, after first levelling the jets with the carb body. According to the description I was working from, the car should have then started at these ‘base settings’ on full choke….. not a chance.
The fuel pump is working as I have a good supply to both carbs, I have a good spark, albeit, the plugs are soaked in fuel. Without the choke engaged, when I stop cranking the engine, fuel runs out of the car at the air intakes for a few seconds. The timing was good before worked on the carbs. Any ideas anyone…..I am thinking the fuel pump pressure may be too high but is this likely with an AC mechanical pump. I am totally baffled and frustrated. I hope the above description of events makes sense.
Richard

[Holiday97]

Hi, sounds like your float levels are wrong or float jets not closing which is causing your carbs to flood.

[manny]

I’ll check. Cheers

[cliftyhanger]

I have had continual flooding problems since I changed the jets on my carbs, which are obviously not the cause. I have been through several sets of needle valves, thjought I had cracked it, but still get occasional flooding.
I did fit an AC fuel filter but I think it is small bits of much getting displaced, I have found tiny specks on the valve seat twice, but it would be easy for them to wash away when dismantling.
I have a fuel injection type filter to fit in the hope it is a finer filter, and that most of the debris has now been washed though. It has still been a great fustration, and the carbs did 20k+ on my last car and never flooded once!

[Richard the old one]

I have found that it is easy to slice a bit off the inside of the rubber hose that is used to connect the carbs when you refit them. It then travels along the pipework and can cause the needle valves not to seal correctly and you end up having to take the needle valve seats out to clear the bits out. It is no good just blowing through the cover pipework.

[Carledo]

There have been a number of more modern mechanical fuel pumps floating about on the supply chain with pressures up to 6.5 lbs PSI when the car needs less than 2 PSI to run perfectly. So it's POSSIBLE for a mech pump to overpressure the system and cause flooding.

Think i'd be inclined to refit the old one for test. Baseline setting the carbs alone shouldn't make it flood, if the only other thing you did was change the pump, the pump is suspect number one.

If the old pump IS duff, I have a Filter King inline pressure regulator here, doing nothing much, that you could try. It's not much use to my EFi engines!

Steve

[manny]

Steve, Clive and Rich, thanks for your replies….all very much appreciated. A friend is making up a pressure gauge so I can check the pump pressure and I am collecting a carb rebuild kit from Rimmers tomorrow. I have changed all the hoses and I shall reassemble with ultra care, given the advice re rubber particules…that’s really useful. I’ll provide feedback when complete.

Thanks again
Richard

[manny]

Okay so I think Steve was spot on with his advice about the fuel pump. I refurbed the carbs yesterday with a kit from Burlen. Initially, I purchased one from Rimmers but several components were not correct!!!! So it was returned…..lesson learned.

I put the carbs back on the car. Set the ‘base tuning settings’ as per the advice on this forum. Went to fire up - still on the untested ‘new’ pump and nothing, other than fuel still flooding out of the air intakes. Very disappointing.

This morning, with renewed vigour, I disconnected the fuel pump and gravity fed the carbs….. said my prayers to the Dolomite gods and……she started straight up. As suggested by Steve, I therefore think the fuel pump is the culprit.

So my questions now please
1. Should I fit an original fuel pump or an electric. I want to ‘future proof’ the car and have reliability.
2. The rear carb was still weeping a little petrol out of the air side intake when I shut off, is this a float height issue.
3. The original float needles were spring loaded. The new replacements from Burlen are not. Will this make a difference.
4. On start up (tuning baseline setting) I could see that the front carb piston was slightly higher than the rear. Would this be ‘ tuned out’ when I get to the tuning stage. I expected them to be the same height.

[Carledo]

Okay so I think Steve was spot on with his advice about the fuel pump. I refurbed the carbs yesterday with a kit from Burlen. Initially, I purchased one from Rimmers but several components were not correct!!!! So it was returned…..lesson learned.

I put the carbs back on the car. Set the ‘base tuning settings’ as per the advice on this forum. Went to fire up - still on the untested ‘new’ pump and nothing, other than fuel still flooding out of the air intakes. Very disappointing.

This morning, with renewed vigour, I disconnected the fuel pump and gravity fed the carbs….. said my prayers to the Dolomite gods and……she started straight up. As suggested by Steve, I therefore think the fuel pump is the culprit.

So my questions now please
1. Should I fit an original fuel pump or an electric. I want to ‘future proof’ the car and have reliability.
2. The rear carb was still weeping a little petrol out of the air side intake when I shut off, is this a float height issue.
3. The original float needles were spring loaded. The new replacements from Burlen are not. Will this make a difference.
4. On start up (tuning baseline setting) I could see that the front carb piston was slightly higher than the rear. Would this be ‘ tuned out’ when I get to the tuning stage. I expected them to be the same height.

1) How long is a piece of string? Aftermarket mechanical pumps are of questionable quality. But so are aftermarket electric pumps. Many of the aftermarket electric pumps (the cheap ones on ebay all seem to be the same Chinese make from 100 different sellers) are also ridiculously noisy. So unless you are willing to pay a bit more for a proper Pacet pump or similar, or a lot more for a proper SU type, a leccy pump could be problematic too.

2) Likely float height or crap in needle valve.

3) Should be ok.

4) if one carb piston is higher than the other on idle, it means either more air is coming through that carb or it has less oil in the dashpot. Either way, it should tune out, but have you slackened at least one of the bolts securing the inter carb link? The idle airfow must be set the same on each carb individually, or 1 screw adjusts both and you will never get the idles even.

Should I dig out that fuel pressure regulator?

Steve

[manny]

Cheers Steve, your advice is very much appreciated. An hour ago I was definitely going back to a mechanical from Robsport. Now I’m definitely going for a Huco electric!!! Who knows what the next hour will bring. The Huco’s range from £35 - £90 for the same pump!!!! I’d rather pay the extra from a reputable supplier but how do you know without recommendation. It’s a friggin lottery. Either way, you can hold off on the regulator for now….but then again….in the next hour.

[manny]

Just looked at the Facet pumps that you recommended. They’re supplied by Merlin Motorsports so going to give them a call tomorrow. Do you know anyone that has one fitted Steve. Spec on output PSI is 2 - 4 which might be a little strong.

[dursley92]

You could try the Facet 60104 which is low pressure and I run that on my Sprint engined TR7. It does make the ticking noise so is best mounted on the rubber bobbins.