Filling the float bowls - electric pump?

[Smokey]

I don't drive my TR4 that often, so the fuel in the SU H6 float bowls evaporates and it takes a lot of starter cranking to fill them and start the car. The owner's manual says to fill them with the priming lever on the fuel pump, but that's a pain. I've thought of adding an electric fuel pump under the car to fill the float bowls before I crank the starter. Has anyone tried this?

[ianc]

If manual priming takes a long time, it suggests to me that the valves in your pump may not be sealing properly. It might be worthwhile to replace the valves - not a particualrly difficult job.

 

I know that Glen Hewett (Protek) fitted an electric pump on the TR3S replica which he built some years ago. As both electric and mechanical pumps have non-return valves, there's no reason why you cannot mount them in parallel, then use the electric pump solely for priming the carburettors (i.e. have it fed via a switch on/under the dashboard). It would be helpful to insert manual isolator valves so that you could disconnect each pump separately, should the need arise. Also, you might want to consider the fitment of a "fuel pump inertia cut-out switch" (as fitted to TR7s), to ensure that, in the event of a crash, the electric pump does not continue to feed petrol - a rather undesirable state of affairs!

 

Ian Cornish

[Smokey]

Thanks, Ian. I have a rebuild kit for the fuel pump, so that will be my first step. There doesn't seem to be much resistance when I use the priming lever. I'll have to wait for some warm weather to get at it - it's just too cold to work in the garage right now. If that doesn't help, I'll try the electric pump route - with an inertia cut-off. Can I mount the electric pump in series with the mechanical one, under the car?

[Richard V]

Thanks, Ian. I have a rebuild kit for the fuel pump, so that will be my first step. There doesn't seem to be much resistance when I use the priming lever. I'll have to wait for some warm weather to get at it - it's just too cold to work in the garage right now. If that doesn't help, I'll try the electric pump route - with an inertia cut-off. Can I mount the electric pump in series with the mechanical one, under the car?

 

Hi,

 

I remember reading somewhere that on engine block mounted fuel pumps the output pressure can be aultered by putting a thicker or thinner packing plate under its mounting flange. This will give the pumps "finger" a higher of lower lift from the shaft driven cam. Perhaps you have an extra thick packer...worth a look. I have an origional pump with priming lever and it gives a definate feel (and sound) of the resistance of pumping fuel when it is pressed, so you are probably on the right track with your valve replacement.

 

Regards,

 

Richard.

[Rhodri]

There is no packing point between the pump and the block. I tried to overhaul my pump and got the kit for a tenner or so. The problem was staking the new valves into a very confined place , and I managed eventually to break one of them and they are not repairable. I then paid out nearly £50, I think, to Mr Moss and got a new, very well made pump with priming lever. I have since seen them advertised for about £30 on ebay- TR Shop? The only downside, for those intent on originality, is that the edge of the diaphragm that you can see, is red, not black. I have only used it for a few hours as the car is not on the road yet, but the suction from a jerrycan of petrol was fantastic.

 

Rod

[vivdownunder]

Smokey, I'm a big wrap for a modern electric fuel pump, as it fills the carbies as soon as you turn the key, and the car starts immediately. Saves a lot of work for the battery and starter.

 

They also maintain a constant supply, rather than up and down with engine revs, and they overcome vaporisation in hot weather.

 

I tucked mine away in a safe place in the rear axle bay where it gets a gravity feed from the tank, with a fuel filter between the pump and the tank to keep the pump clean. If you want to go to the trouble, you can run the fuel through the manual pump so the car looks original. Just cut off the activitation lever and remove the valves. You can use a TR5 safety switch, but there are better ones these days.

 

With the choice of electric pump, I have a (nearly silent) rotary low pressure unit I fitted some 12 years back, but today I'd go for one of the electronic models of which there's a wide choice. Select one with a pressure range of 1.25 to 2.5 lb/sq inch for either SU or Stromberg carbies, so you don't need to add a separate pressure regulator.

 

Another reason is the quality of repro parts. I've seen new manual pumps break off mounting lugs, and diaphragms in repair kits that don't like either ethanol blends, or unleaded, or they just split through poor quality material. The best solution if retaining the manual pump is to rebuild the original, and use a branded repair kit from a carbie shop, rather than a plain box version.

 

Regards,

 

Viv.

[MikeF]

FWIW:

I have reconditioned my carbs, plus new pipes etc on my 4, so no leaks. The float chambers retain enough fuel that the engine will start immediately after up to 10 days standing, after that a crank or two is required. The picture is a bit muddied as I think it gets bit oily or something if left longer. It will take several cranks to get going after long periods even if I hand prime.

I had considered an electric pump for all the reasons given, but there doesn't seem to be that much benefit for the cash/time outlay. So in spite of all the logic I used some of the cash saved to buy some airhorns instead. They have no benefit at all of course, but they sound great!

 

Mike

[ianc]

If there's little resistance when using the hand primer lever, it suggests that the valve(s) in the pump are leaky, so should be replaced.

 

If adding an electric pump, it would be better to place it in parallel with the mechanical pump, not in series. If in series, the electric pump would be pumping through the mechanical pump or vice versa - not a good idea, as there would be some flow restriction from the inactive pump. This means that the best place to mount the electric pump (so as not to have two long runs of petrol pipe, as would be required if the electric pump were situated in the boot) would be in the engine compartment, along with isolator valves and inertia safety switch.

 

Ian Cornish

[adriantr4]

Hi

 

I was in the fortunate position of being given an old TR3 pump with the priming lever. I rebuilt it with the standard kit, so when I want to start the car (a tired '4) I just give it a few pumps and off we go. I can feel the carbs filling.

 

On a related thread, years ago I put Grose valves in the carbs after worrying fuel leaks with the orginal pointy valves, and they work fine to this day (Even further back I had an MGB GT whenI cured of the same ill)

 

Dont read the forum much - good luck.

 

Adrian & TR4

[lynchpin]

Hi

I tend to agree that you might have a problem with the pump as i can leave my tr4 for a couple of weeks or so and it still only turns over a couple of times before starting.

 

Cheers Phil.

[Dick]

Reference red and black diaphrams....

 

I heard somewhere that the original black ones don't like modern unleaded and the red ones are specifically designed to be compatable with unleaded.

 

I also had a car once....may have been a Bristol...memory fade...that had a Bowden cable arrangement fitted to the priming lever with a control under the dash so that priming could be done from inside the car........If I were going to do anything this is the route I'd go.

 

My own 3a used to need to be primed but after I fitted a new high inertia starter motor...that turns the engine much faster...I have not had to prime even after standing for weeks.

 

Regards Dick.

[BrianC]

My own 3a used to need to be primed but after I fitted a new high inertia starter motor...that turns the engine much faster...I have not had to prime even after standing for weeks.

Ditto.

However, I prefer to turn the engine over for a short time before it starts, just to spread the oil around a bit, so I don't pull the choke out until I've done this.

[tthomson]

Hi Smokey,

 

I fitted an electric fuel pump on my TR4A in the early 1980s after the mechanical one failed. It worked fine. It was a low cost one (I was pretty strapped for cash in those days). I fitted it using a piece of metal from a toilet cistern (unused for its original purpose), and located it on the Left hand wing. I continued to use this for a number of years with no detrimental effects. With the rebuild I am going through at the moment, I will be returning to a mechanical pump. Mainly because it looks better than a cobbled together solution, but I still have the electric pump should I need to use it.

 

TT

[Smokey]

Hi again, and thanks for all the input. I rebuilt the AC pump this weekend with the Moss kit (new diaphragm and valves), but there doesn't seem to be much improvement. There was only a regular gasket to mount the pump, and I renewed it. The carbs are rebuilt units from a reliable US specialist, so I think they're standard in terms of fuel evaporation. The H6 float bowls are basically vented to atmosphere; I believe the later ones hold fuel longer because their venting is different. I never had this issue with my 1965 TR4 with Strombergs. The owner's handbook says if the car has been sitting a few days, use the priming lever.

 

Rod, the diaphragm in my pump was an original AC spare, and it was red in colour, so I believe that red is actually the correct original colour. Adrian, re the Grose jets, I installed some in my TR250 in the early 1990s, and they worked well, but the specialist who rebuilt my carbs said the current ones are of poor quality.

 

The priming lever on my pump doesn't seem to work well, and it could be an internal mechanical problem. The valves are now new, although given the quality of today's parts, they could be faulty. I find the probability of any new part actually working is about 50%.

I plan to show the car one more time at the Trimph Register of America meet next year, so I will keep it original for now, and then probably go with and electric pump. Or just drive the car every day so I won't have this problem .

[Smokey]

I tired the priming lever again last night, and I got resistance for about one and a half strokes. I could feel the fuel moving, and then there was no resistance. The lever moves, but doesn't seem to pump anything after one stroke. The valves and diaphragm are new. I couldn't figure out how to remove the shaft, levers and spring, so I didn't touch that part in the rebuild. Could the pump be assembled incorrectly? I have found many bodged repairs as I progressed through the car over the last three years.

[Rhodri]

No more resistance means that the carbs are full- sounds as if all is OK.

 

Rod

[Smokey]

Thanks, Rod - that's good news. It started easily last night, and I'll try it again after the car has been sitting for a few days.

[Smokey]

PROBLEM SOLVED! I got some advice from the master mechanic who works on my car in areas beyond my competence (which means most areas) and the problem turned out to be much simpler than I thought: the choke wasn't out far enough. The jet needs to drop about 3/16", and by pulling with two hands on the choke cable and adjusting the linkage, I was able to do that. The car started instantly and went to full revs, whereas prviously it would cough and sputter and die. So it was short of fuel, but not because of the pump - it had too little choke and thus too lean a mixture for starting. So that seems to be that - lesson learned.