Loss of power after filling up with fuel

Hi Phil

Have you manaed to find the culprit.I have exactly the same problem.I have also had my fuel system checked,as well as the carbs reset,but to no avail.I have also replaced the fuel pump from 0.25bar,to a 0.5bar.
My car drives ok for a while and then starts to surge( fuel starvation) .i was at a show and on the way back i had to physically stop,and then pull off again, where the car would drive ok for a short distance and then the same trouble starts again.You will agree it is very frustrating.One of my mechs indicated that i need to replace the advance / retard unit,unforunately theses are hard to find in RSA.Do you think this may have something to do with it? If i rev the motor when she is stationary it revs fine,however once the motor is under load she then has the symptoms.I have also drilled a little hole in the fuel filler cap to see if it is vaccum related,to no avail.I now don't know what to do or where to look,as all the obvious culprits have been re-looked at.I have been struggling with this since feb 2010, so you now know my frustration.
Hoping you / someone has a solution.Regards
 
winston wrote,...
One of my mechs indicated that i need to replace the advance / retard unit,
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Hello Winston,

A vacuum advance module that no longer works won't result in the surging that your Rover is experiencing. The only tell tale sign that you will see is an increase in fuel consumption, most notable on highway driving. Apart from that, there will be no performance change at all.

Fuel starvation could be from a number of sources. Incorrect needles within the carburettors, incorrect float levels, mechanical fuel pump diaphragm in need of replacement. By the sound of it, your fuel pump is electric. Where abouts is it positioned? Within the engine bay? The use of Winter grade fuel during warm weather will also see surging and vapourisation.

Ron.
 
Hi ron

When i bought the car one of the diaphragms needed replacing .this was done with the correct part,and i also had the carbs balanced and set.The car drove better but still had the same surge.I then filled the car as Phil had mentioned as well and it seemed that all was well until the tank was at half full.this led me to believe that it may have a vacuum,but this was quickly erased once i had the hole test.All other componenets were found to be correct and at an acceptable condition by the person (75yrs old) whom i had carry the work out.He used to work on these cars in one of the showrooms at the time.I had also installed new needle & seat valves as a precaution once again (the correct ones as supplied by a specialist)

The fuel pump is positioned under the right wheel arch (rear) .I think it is still of the mechanical type.The carbs were also removed .cleaned etc and balanced as said above.i have thought of putting in a second fuel pump closer to the motor to assist, but don't know if this will solve my problem.As soon as you stop at a robot /stop street . you can pull off with no issues.I was told that the bowels were set properly .
 
Hello Winston,

Just to be clear, does your Rover surge or hesitate? What speed are you doing when it occurs?

Ron.
 
Hi, remove and drain your fuel filter, blowing through the output hole and collect what comes out in a dish.. see what comes out and if there is an improvement?
 
Hi there
If i pull off then i can accelerate to around 80 - 100kms/h ,for around 10 - kms, and then she starts to hesitate (jerk) as if there is no fuel.You can here that the pump is running and pumping strong enough.I then take my foot off the accelelrator a little so that the bowels ( i assume ) fill again, but sometime i have to physically stop the car, put it in park and wait 5 sec and then slowly pull off again. One of my colleagues suggested that i have a look at the float chamber to see if there isnt a rubber or something that is blocking thefuel exit.I As i said befor i have had then whole fuel system checked out to no avail.I have also repalced the fuel filter on a number of occasions,but will try this again,as it does not look dirty.
 
Hello Winston,

If the floats are set to less than 40 thou ( HIF6 carburettors I assume? ) then insufficient fuel will be within the bowls and the engine will run lean. If the fuel pump cannot supply sufficient fuel to ensure that the bowls are always full to the correct level, then the engine will run lean and hesitation will result. Sadly I have to say that just because you paid to have someone check out the fuel system, does not mean that you can be certain that the work was carried out correctly.

What sort of pump are you using and how was the fuel pressure increased to 0.50 bar?

Ron.
 
Just noticed this thread, I will add my 2 cents to the discussion. To me this sounds exactly what my V8 used to do, after the engine was turned off and then restarted a few minutes later i had the exact symtoms, turned out to be heat soak affecting a dodgy electric (engine bay mounted) fuel pump.

Graeme
 
In terms of the bowels, this has crossed my mind,so i had spoken to the guy who helped me(he had worked for rover in their workshop when they were in SA,and is around 70 years of age.He had also worked my mates mg midget,who was extrememly satisfied with the work.he had indicated that the bowels are correct. unfortunatley ther are not alot of specialists or garages that are willing to fiddle with these carb's.His recommendation was to replace the then fuel pump (this was 0.25 bar).I had this done at one of our local auto electrician shops.and found that there was no improvement.They then suggested a stronger pump (0.5 bar) which then felt better in the beginning,but after a while i had the same symptoms again.
 
If you drive it hard and switch off as soon as it starts to hesitate, then turn the key back on to activate the pump, does it race like it's run dry or is it ticking along as if normal?
If it's racing due to starved supply, then the problem is tank-side and if it's as normal then look carb-side.
 
Dave Herns wrote,...
Which diaphragms are these ?Made me think the car had Strombergs (?) like the early Range Rover
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I took it to be the mechanical fuel pump diaphragm Dave, of which there are two. Guess we'll have to wait for confirmation from Winston, maybe his Rover does have Strombergs.

Ron.
 
Winston,

Does your Rover have an electronic ignition system or are you still running points? Have you tried a different coil perchance?

Ron.
 
As far as I am aware my car has two SU carbs.In terms of the coil i havent tried this,but would this not have an effect if the car was idling? as she idles smoothly wth no missing.The diaphragm i am refering to is where the carb would bolt on to the main block,as it was leaking originally.I will also try the suggestion regarding the switching off the ignition,and see if it races.
 
winston wrote,...
In terms of the coil i havent tried this,but would this not have an effect if the car was idling?
Click to expand...

Not necessarily. You can test the coil by measuring the primary resistance, which for the original Lucas 16C6 coil is in the range of 1.2 to 1.4 ohms typically.

Ron.
 
ron
thanks for you help.I am taking my rover in today to replace thespeedo cable and will ask my mech to check through your suggestions as well . Will let you know in due course if it solves the problem.
 
Hi Phil

I removed the fuel filter and blew through it .There was a no. of small sandlike deposits,put it back and then took her for a run.As my speedo cable had snapped,i decides to drive her a around 4500 rpm (thinking that the engine would rally be working here) for around 30kms.I think this solved the problem,as she did not "jerk "once. I await the return of my car, once the speedo has been repaired.

I also spoke to another gentlemen, who had the same issue with his rover,and he did the same and says it has been behaving for over a year now.What does puzzle me though is that i replaced the fuel filter nottoo long ago,andit still looked clean.I could not see any deposits while the car was idling,but took your advice anyway.Thanks very much.
 
Hi Winston, so the filter was restricted then? I have had similar problems before. Glad all seems ok now though! :D
 
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