Electric Fuel Pump

ron110250

ron110250

New Member
I've been reading up as far as I can on this and need some advice on fitting an electric fuel pump to my recently acquired P6 3500 Auto. I'd like to fit it at the front, it seems a lot of work to fit it at the rear! and would like to keep it as unintrusive as possible, retaining the old mechancial pump in body only. Any tips, hints etc would be appreciated.
In true form I conked out last sunday after doing a quick trip to take my son to the station, a hot day and nearly at the top of the hill and it just died on me. No mobile phone, no change in my pocket but I had my wallet with the recovery card. The AA man diagnosed a duff pump and I haven't yet had a chance to investigate further, I hate it when the nights pull in a short time after getting home! I will investigate at the weekend to see exactly what has failed. All the advice seems to be to fit an electric pump and looking at JRW's price list the service kit is roughly half the price of a front mounted electric pump kit so probably better value to go electric.
 
Hi Ron

All the advice is most certainly not to buy an electric pump!

First off, fitting an overhaul pack to the mechanical pump is cheap, quick and easy, so do that anyway.

The cause of fuel vaporisation is usually something else not correct. Prime suspect is always the coolant flow through the inlet manifold. There is a hose comes off the manifold back to the top of the radiator from the "tower" between the carburettors. The manifold often blocks just inside this pipe outlet. Rod it out and make sure you can see a flow of coolant coming back to the radiator from it. Next is an incorrect thermostat fitted. The P6 needs a bleed hole in the main body of the stat to allow coolant to continue to pass a closed thermostat. This should be located at 12:00 when viewed with the thermostat cover off from the front of the car. These two faults, when rectified, will then allow you to properly bleed the cooling system. Finally, an error in the engine tuning, particularely incorrect timing, may well cause problems this way.

I'd recommend getting these right first. Then if you are still in trouble, by all means fit an electric pump. JRW only sell Facet pumps, which are noisy, cheap and are not necessarily suited to the application. You really want a rotary pump that is designed for use as a lift pump rather than a pusher pump. And don't forget that carburettors don't like lots of pressure - 4 to 5 psi is fine. A suitable pump is:

http://www.gowerlee.dircon.co.uk/HUCO.html

When fitting it, simply mount it in series with the mechanical pump - no need to remove it's innards! The front corner of the engine bay is probably the best and coolest location and allows a neat jump for the fuel pipe over to the old mechanical pump. Also take the new fuel line required from the firewall/bulkhead area, onto the inner wing - either inside the engine bay, bundled with the wiring loom, or outside the engine bay in the mudguard area. For the latter route, exit the engine bay behind the steering idler and re-enter close to where the wiring passes out to the front side lights and indicators.

For the overhaul kit, I'd try the other suppliers as well - Ian at Rover-Classics and Geoff at Wynn's, not to mention the ultimate source of P6 spares - E bay!

Hope that helps.

Chris
 
Wot Chris said! I went the route of an electric pump to cure hot weather slow traffic by locating an electric pump up front and yes it cured my vapour woes however it is not the ideal situation and ultimatly caused me many problems. Down sides to the electric is you need a fuel shut off switch (automatic) for the pump in the case of accidents (pumping fuel sparks fire, death and destructuion etc) also the damn things tend to be noisey plus if you fit them in the rear you need to do a lot of mucking about to get the reserve to work and mounted in the front there is a tendancy for heat build up in the engine bay to negate the curative effects of going electric.

PS I have since reverted back to my origional mechanical pump and am a happy camper again. :roll:

Graeme
 
Thanks for the info, nearly made a big mistake there didn't going electricI. I've just had the chance to go out and look things over. Put the key in, turned it over and it fired up and was chugging along nicely so looks like the pump is fine after all and it was up a steep hill in hot weather after all. I must admit the engine did smell warm even though the temperature guage hadn't moved that much, it didn't spit or splutter at all, just died. I also had a pretty full, at least 3/4, fuel tank. Is it likely that the pump is weak, does that happen or do they either work or not?
 
Hello Ron,

If the engine just stopped without any prior warning, then that does sound much more like an electrical problem as Rich mentioned, rather than fuel related. Mechanical fuel pumps which are in need of an overhaul will typically result in hesitation when climbing a hill, similar symptoms when fuel vapourisation occurs initially.

Ron.
 
Its my beleif that fuel vapourisation is not a function of engine heat so much as engine bay temperature. If you are traveling slowly up a steep road there is less cool air being forced thru the engine bay due to low speed. It is in these conditions RV8's fail with fuel vapour problems even if the rest of the system is in good factory order. A previous owner of my car when it was new recounted many instances where traveling up steep prolonged inclines where this occured.

So I would not rule out fuel vapourisation as your cause of failure, as Chris documented there are some very good cures of this factory induced fault, I would be inclined to follow the rerouting of the fuel line aspect.

Graeme
 
I still have the same problem in the back of my mind , and i would say that it is worth , while the pump is off the motor , make sure you do the valves in the pump body , You may be supplied with small valves in your kit , but have big valves in your pump . Order both and fit accordingly . It is a bit of an ass removing them , grinding out the staking marks , then staking them back in , but i did it ! :) and then you've ruled out another possible problem !
Wha'dd i know!!!
Ps out of desperation i sat on the garage floor two weeks ago pumping the cam lever up and down aginest the wall with my fingers and thums blocking and unblocking the inlet and outlet until i was satisfied how it worked . Then rebuilt it properley thus ruling it out ! then moved on and found my problem , ( witch is not likely yours within the carbs )
Hope this helps rather than confuses !!! :? :)
 
ghce wrote,...
Its my beleif that fuel vapourisation is not a function of engine heat so much as engine bay temperature. If you are traveling slowly up a steep road there is less cool air being forced thru the engine bay due to low speed. It is in these conditions RV8's fail with fuel vapour problems even if the rest of the system is in good factory order. A previous owner of my car when it was new recounted many instances where traveling up steep prolonged inclines where this occured.
Click to expand...

Hello Graeme,

It is interesting that the occurance of fuel vapourisation seems to present with different circumstances in different parts of the world. Here in Australia which by and large is a hot country the frequency with which it happens seems to be far less than in countries with cooler climates.

Ron.
 
It might well be due the far far higher numbers of P6 in both the UK and NZ, and the bell curve probably dictates that there are more cars in the prone to vapourization bracket than Australia, it may just be simple mathmetics.

Graeme
 
Could also be down to perception and maintenance, in the UK we expect the temperature to hover around 0 degrees most of the year, so we're never expecting anything to overheat, whereas you're ready for higher temps and probably maintain the cars better.

Similar thing applies to snow conditions, most of Europe copes fine with significant snowfall, but in the UK we're stuck after a couple of inches, just not prepared for it.
 
Thanks again for all the info, just remembered something else to add in. When the AA man was checking everything over he commented that I had a strong spark going into the distributor but it was a bit weak coming out, he also noticed blue flashes around the top of the coil. Even though he couldn't start the car it did fire very briefly when he sprayed damp start into the air filter. I think I need to do some basic servicing, replace the distributor cap, rotor arm, points and coil and overhaul the pump, I will also check the water flow as suggested earlier and see how it goes from there. As i've only had the car a short time a bit of basic maintenance wouldn't go amiss even though I drove the car home 100 miles without any hickup.
 
This supports what Rich said about an electrical fault, sounds like you maybe suffering what is rapidly become the dreaded ignition component failure sydrome. Lots of new stuff is just plain rubbish especially rotor arms, caps and condensors, plus others have had problems with brand new coils as well recently.

I'm not sure of a good recomendation for supply of reliable parts, maybe some others could offer advice.
 
Simon bbc . Highly recommended , you can always talk to him on the phone , and any problems he,ll talk you through and no quibbles if you suspect a part he,s supplied . He,s even sent me replacement stuff that turned out to be o.k . If you play fair with him cant reccomend him highly enough .
 
Just been doing research on Electric Pums and mechanical pumps. Spoke to Wins as Chris had suggested above. No more big valves available for the mechanical pumps, so looks like electrical is the only option.
 
Wadhams still have the big valves listed separately £16.00p per pair (standard repair kit has the small ones)
No guarantee that the stock level is accurate - ring them Tel. 01384 891800

I have all the kit to go electric when the need arises, but I will stick with the mechanical pump until there is absolutely no option of repair,
going electric imho is a compromise and dependant upon the expertise of the "converting mechanic" can be a nightmare.
 
The Facet I fitted to the P5B is noisy, although I only use it to prime before starting & I didn't put it on the proper cotton-reel mounts (although I think I used rubber washers as a compromise). It did come in handy at the Enfield Pageant as I started to get vapourisation for the first time ever, just as I got to the RSR stand which it cured without fuss.
 
Wadhams will only sell the big valves seperately if you firstly bougght the small valve kit off them. Otherwise they sell a large valve kit. the problem I have with that is that it could be wear in the link arm or the engine cam that is causing a low lift, so i am going to go the electric route. If i ever rebuild the engine, i will look at rebuildign the pump completely.

I got a kit from http://www.fuelpumpsonline.co.uk/facet- ... it-8-p.asp as it contains the rubber mounts, inline pre filter and fittings.

i will be the converting mechanic and therefore have no concerns!
 
I've rebuilt my fuel pump, and during normal, even spirited driving have absolutely no problems. My problem occurs on hot days when I get stuck in traffic. My car has suffered from fuel vapourisation before, it was ticking over ok in a jam, but experienced a distinct lack in willingness to rev when the traffic started moving, followed very soon after by the engine cutting out & not restarting. Once cooled down. it started ok, and driving along at normal speeds, all was well again. I've checked the coolant flow from the carb tower, and all is well. I've also now fitted an electric cooling fan, but its now doubtful that I was actualy overheating (see my fuel pump woes thread). I've got a facet type pump I plan on fitting to use only when needed. On that basis, I was planning on fitting it to the reserve line, so that under normal circumstances, the mechanical pump draws fuel straight from the tank on the main fuel line, and the electric pump is not even in the circuit and switched off. If I then get a fuel vapourisation problem, which is normally only in a jam, I can pull the reserve tap and switch on the electric pump to get me going again. Once moving, I can revert to the main fuel line, and switch off the the electric one.. Does this sound like a reasonable idea? The added bonus to this is if I'm running on reserve & low on fuel, then the weight of the fuel is not there to help prime the mechanical pump, so the electric one can be deployed if needed, although by all accounts, the mechanical pump will happily pull fuel throughthe elctric one. Thoughts on this idea?
 
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