Hot fuel pump - Fuel starvation or not?

R

Rovertron

Member
This is a bit long as I'm a bit foxed by this.

So I lost my fuel starvation cherry last Friday and I ran the battery down trying to restart it. So feeling a total idiot I had to call recovery. Ok, driving on a sweltering day (it was 90F) and getting stuck in traffic for 10 minutes didn't help. The Kenlowe kicked in as it should but the car conked out about 400 yards down the road when the temp gauge was on it way back to spot on 85F.

The recovery chap said the pump was very hot despite being stuck at the side of the road for almost an hour. He poured some water on it to cool it, ran the fuel round on the starter, plenty of choke, bit of quick start to give the carbs a nudge. No probs, off again and negotiated some lengthy waits at traffic lights and 5 miles without a hitch despite the ambient temp.

So I went out on a 'diagnostic' run tonight, it was a fairly cool night (about 72F), the engine was on the button for temp (I watch that dial like a hawk) and 25 miles in there was a big flat spot above 30mph on the open road, it didn't clear itself so I had to pull over. The engine stopped but then I restarted it with no choke, so I pull the choke to get the fuel in and the idle is all over the place. Got to the boot, pulled out the 5L bottle of water I keep in the boot and poured it liberally over the pump and it seemed to settle down again.

Another 2 miles on, again, big flat spot at 20mph this time but managed to limp to a lay-by. Out again, more water on it and quick readjust to the Kenlowe to switch it on. 5 more miles without any incident but I stayed well away from traffic and lights, I got the car well up over 50mph but again at 60mph, flat spot again!

I get the car home, idle fine, Kenlowe running, left it for a few mins, temp spot on.

I've clocked up almost 1000 miles in the last three months in it with only one occurance very early into that of a potential starvation when the engine topped well over 100F in traffic. It cleared once I got some cooler air into the engine bay. Since I put the Kenlowe in it has kept the engine cooler (kicking in at a good 95F) and there's plenty of coolant and until only Friday, even in traffic the Kenlowe has performed admirably even on very hot days and keeping everything running as it should.

So I'm foxxed and left with three possible causes.

Dirty fuel? (I had some wandering hands in the car attached to my 4 year old nephew who pulled out the fuel reserve knob recently whilst I was in the garage paying for the fuel!. This is a worry as I have no idea how the reserve works, never touched it and the car is a recent acquisition but I know may have some old fuel in there.)

Worn pump? A flat spot at speed, an inability to pump more fuel and getting hot does suggest a soon to expire pump to me.

Fuel starvation? But the engine temp has been fine although the exhaust manifold temps are pretty fierce.

I am determined to nip this straight in the bud simply by replacing the pump if needs must. However, if it is a simple case of driving the dirty fuel out of the system (it's 1/3 full now) so be it.

I'm very new to V8's having previously had a 2000TC which despite tin worm never missed an engine ignition :)

Can anyone help?
 
Well, seeing noone else has replied yet.. I'll give a go..

It's not your fuel reserve tank. That only operates a 2nd tap to the bottom of the tank (5 gal I think). I use reserve every now and then when I'm on a long straight run to refresh the fuel in that line.

I've had a couple of dead spots like that, I pulled over shut off, then restarted and all okay, happened twice to me now and the temp outside would've only been 17~20 °C.

The ex owner (20+ years) of my car said it happened and was related to the damper pistons jamming.

I gave them a good thwack, checked the oil levels, thwack again and haven't had the prob again in the last 6 months.

Not to sure what a kenlowe is, I guess elec. radiator fan, or meybee fuel pump like the mini I had.. If it's running hot, then i'd say certainly points to it being faulty. Is it running full~time, back to the mini when I turned the ign on the first thing I heard was the fuel pump for 1~2 secs.
 
AAAGH I just re-read you post, DON't USE QUICKSTART... I've heard of it rooting older engines... something about it running too hot.

Also if your pump was hot after 1 hr (assuming the ignition was on) replace-recondition the bugger! It must have a short in it.
 
A kenlowe is an electric fan ran on a thermostat placed in the rad through the top hose.

I was very reluctant to use the quick start as I totally agree with you there, but there was fuel running through but no ignition.

I'm all for a bit of whacking something with a hammer, where is the location of these damper pistons, are they in the pump themselves?

I am also of the opinion if it's the fuel pump then replace it, simple. It looks a very easy job in the workshop manual. They recommend taking the fuel line to the pump from the reserve tap setup off, removing the line to the filter and unbolting the pump in that order. Personally I would reprime it by getting some fuel in on one line before reconnecting to the filter.

What do you think?
 
I assume you're talking about the mechanical engine driven pump? It's easy to physically remove (two bolts) but difficult to prevent fuel loss. The Haynes manual tells you to plug the union, but how? This solution may help.

I had to remove the pump yesterday because it was dripping fuel from a gasket. To make it worse I had a full tank (only 4 miles driven). Having lost about a pint of fuel when removing it the first time and unsuccessfully plugging the union, I found a method to remove/replace it in a couple of minutes without losing more than a cupful of fuel.

Get a long piece of 1/4 fuel hose. Undo the inlet to the pump (1/2" AF). Remove the pipe from the pump and quickly push the hose over the olive on the pipe. Put the other end of the hose above the fuel tank level to stop it draining. Remove the outlet pipe if necessary and then remove the pump from the engine.

Replacement - ignore the Haynes "refitting is the reverse of removal"! Do not attach the pump to the engine first as this makes it hard to align the threads on the unions and all the time the threads are loose,fuel will be p***ing out.

Attach the outlet pipe to the pump and put the pump roughly in position against the engine. Remove the hose from the inlet pipe and push the pipe hard into the pump body so the olive makes a seal. Screw the union in (with the pump loose, this should be possible by hand). Do not fully tighten.
Attach the pump to the engine and tighten all connections.

The most nerve wracking bit (this being done about 3ft from a busy road) was somebody chucking a fag out of a car!
 
Hi

I am assuming that the fuel pump is mechanical - i.e. fixed to the side of the engine on the nearside just behind the fan belts? If so, this will get hot in service as will the engine block and this is nothing to worry about (unless it glows red hot!) If it is hot enough to touch it should be at its operating temperature, if you cannot touch it then the engine is running far too hot.

In my one and only experience of fuel vapourisation, it was the off-side bank of cylinders that would not run, heat from the engine caused the fuel in the line to vapourise and the engine ran like a bag of old nails.

An engine in reasonable condition, correctly set up with a good radiator should not vapourise, the only time I had a problem was a result of a head gasket failure - last summer on the hottest day in heavy traffic the engine got hotter than normal, but still in the green section and did not miss a beat.

Your engine could be getting unduly hot and I would suggest you check the dwell angle on the points, then the timing, check the fuel - I use Shell Optimax and the car goes really well - no real need for an additive. Have the flow rate on your radiator checked and it will probably need to be re-cored.

The piston dashpoints the other person referred to are in the carburetor, un-screw the black top and lift up, fill with oil (engine oil is recommended although some people use a light machine oil) and top-up.

The fuel in your tank is less likely to be contaminated than on other cars of the same age as the tank is less exposed to changes in temperature and therefore less susceptable to condensation. Fuel is likely to be fairly clean. However, your fuel pump is probably not as effective as it was and the diaphram may require renewal. An overhaul kit is available from Wadhams and these come up on ebay as well and this would almost certainly improve matters. You can plug the end of the pipe to minimise fuel loss and the whole operation should take about an hour although it is fiddly and patenience is required! Obviously do the work when the engine is cold otherwise you will burn your hands!

As for the fuel reserve, this is just a tap on the off-side, approximately below the steering box, remove the ail cleaner assembly and you will see it - the fuel line moves accross from one side of the car to the other above the gearbox bell housing at this point. Reserve take fuel from the bottom of the tank and it is approximately 2 gallons.

good luck

Gary
 
Thanks again, some great advice there. I do have the workshop manual and it recommends taking the feed from the reserve tap and to the filter off first. It's the reserve tap feed that looks the most troublesome.

The rad is brand new and also not losing any fluid at all, the rad cap holds the pressure well. The Kenlowe really only comes on after 5-10 mins in traffic and holds it firm at 90.

As for the timing, I do use Optimax and have noticed a slight knocking under hard acceleration so I'll double check this again. My concern is it is the engine running overly hot rather than a knackered fuel pump mainly due to the fact it does get warm quickly from startup and also the temp does seem to rise in traffic after only 5 minutes stationary. It's also far more expensive should the engine go bang!

The tank is 1/3-1/2 full and getting the pump off without a petrol spill is my main concern too.

If it is a pump replacement job, I am tempted to let the big boys at the local garage do this, it'll be an hour tops for labour to replace the pump and they have more experience of handling petrol than I do.
 
Rovertron.
I can simpathise with the car stopping on you. I had exactly the same problem about 8 years ago with my blue V8. It did all the things that you described in the middle of a summers day on the Sydney Harbour Bridge! Very embarassing.
The soution was to fit an electric pump. Simple and only $200 Aus fitted. All I did was to blank off the hole for the mechanical pump with a piece of sheet aluminium shaped to fit with a gasket behind it. I them covered at least 150000 miles with this mod in place and never had a fuel vapourisation problem again.
The pump lives under the rear drivers side guard and bypasses the reserve tap.
This is another option for you if you really want absolute piece of mind, but the mechanical pump on my 2000 lasted 300000 miles with no problems.
One other thing, check that you coil is not overheating, this caused no end of trouble for me with my old Range Rover. Cheers
Guy. :D
 
The previous owner of my V8 had replaced the standard mechanical fuel pump with a Facet 'Silver Top' electric pump, mounted in the front of the engine compartment behind the left headlights, and with the new fuel lines running beneath a bit of aluminium 'baffling' (?) to try and reduce vapourisation in the lines. Yet on hot days in deadlocked London jams last summer (during the really hot spell) I suffered similar problems... I don't know if that's helpful information, just wanted to let you know that fitting an electric fuel pump might not neccessarily cure your woes! I've also been told that my fuel pump is gravity fed and therefore is struggling to suck the fuel from and lift the fuel above the tank. Furthermore another P6 owner told me that placing it at the front of the car increases the risk of a fuel fire in the event of a front collision. I dunno, I'm a rookie, an enthusuastic owner but in no way a skilled or experienced mechanic!
Good Luck! If you replace your manual pump see if you can fit the electric one at the back of the car under the tank, I suppose...
Good Luck!
 
Just thought I'd update you all. In the end the car completely died, nothing at all so I was stuck having to do it myself including a hairy moment of shoving the car out of the garage and then jumping in to stop it.

Ray Weekly (god bless him) came up trumps with a recon'd unit for a fairly reasonable price as I was told they are getting a bit rare. So loosened the bolts, many, many thanks for the tip on the inlet, that line can really leak it out. As luck would have it an old washer jet pipe from a Mk1 Fiesta I had in a box of old spares is a perfect fit and pushing in a few inches of it and using a gravity effect, it halted it to a mere drip. Getting the pump off was easy enough, however, then the trouble started.

There's no easy way to relocate the cam that drives the pump. "Refit is a reverse of removal" isn't very helpful from the workshop manual. My first attempt came to nothing and I had a terrible realisation that the filter might also be blocked. So that came off as well, I wouldn't recommend the next bit unless you like the taste of petrol but a hearty blow through it confirmed everything was ok there. I had terrible thoughts of a low loader, big bills and a mechanic sucking in air through his teeth talking serious notes.

So I had the pump off again, lines off, felt for the cam this time and found it, so to fit the pump this time from the bottom of the aperature and up to marry it to the timing cover seem to feel 'better'. I left it a bit loose as the inlet needs a bit of jiggle to get the threads to line up. So inlet back on, more fuel peeing out until the union thread went in to finger tight.

I thought I'd prime it this time to remove the doubt of airlocks and left the outlet disconnected. A quick turnover soon confirmed that everything in the replacement pump was fine as it was soon leaking fuel through the outlet aperature. Outlet on, filter on, primed the filter by turning it over a little bit to make sure that wasn't blocked, all ok there. Top line from the filter on, tightened everything up.

Got in, bit of choke, turned the key and first time !! Big roar from the engine, back of the net!!!

So, took the old girl out feeling very smug and got into a bit of traffic, not a problem, it definitely feels much more urgent on the throttle and picks up much, much better. I can't believe I didn't notice it before. No knocking under heavy acceleration unlike before so the timing must be spot on, had to be the pump.

Still, for a 35 year old pump it gave great service. No doubt all recon'd back up it'll good as new for someone else.

So thanks again to you all for the advice, as I'm a bit of mechanical novice, I'm feeling very pleased for myself !!

I'm certainly going to consider an electric pump perhaps for the future but I think this one should fine for a while to come.

So I can get back to the list of things that really need doing, anyone know where I can get a pair of rear axle springs! I'm feeling brave ;)
 
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