75 P6 V8 - Bye, this car

[Squire_Dawson]

So I wonder if its purely down to old age or something to do with the OMG ETHANOL in modern petrol?

[dollywobbler]

I enjoy this thread and apologise for the enjoyment of such suffering. The grumpy cat comment was the icing on the tank.

[Conrad D. Conelrad]

BROKEN.

 

Joining a motorway yesterday it started to struggle. Struggled to get up to 50, then really struggled to maintain it. Drives perfectly at town speeds, but the faltering can be felt during harsh acceleration. 

 

So, what is it now? Obviously, the stuff I changed the other day is the first under the spotlight. I checked all the connections,  and I changed the fuel filter again in case the new one was dodgy. I wondered if the new pipe coming out of the tank was too restrictive, so I tested the flow of the fuel pump:

 

 

That's about 100ml in seven seconds, which looks pretty healthy to me. If I'm still getting this much petrol arriving at the carburettors, I can't see how the problem could be with my new fuel tank.

 

So what, I have to start messing about with the carburettors? I just got the car tuned up so I didn't have to mess with bloody carburettors anymore!

 

Watch this space. For my forthcoming self immolation. 

[Junkman]

You can clean out the carbs without altering any settings.

I wonder whether the problem is ignition related?

[forddeliveryboy]

Does the leccy pump run at the same rate all the time or does it deliver more as revs rise? I'm always suspicious of aftermarket electrical goods.

[Conrad D. Conelrad]

  On 01/11/2016 at 17:06, Junkman said:

You can clean out the carbs without altering any settings.

I wonder whether the problem is ignition related?

 

 

I'm not concerned about altering settings, I'm concerned about having to undo all those damn nuts again!

[Conrad D. Conelrad]

  On 01/11/2016 at 17:12, forddeliveryboy said:

Does the leccy pump run at the same rate all the time or does it deliver more as revs rise? I'm always suspicious of aftermarket electrical goods.

 

Constant. 

[LC Torana]

  On 01/11/2016 at 17:06, Junkman said:

I wonder whether the problem is ignition related?

+1

 

Get out thy timing light.

[worldofceri]

Though I would likely throw myself under a train (or possibly a dark horse) were I suffering the tribulations of the protagonists of this thread, it is nevertheless chock-full of lolz.

[spartacus]

99% of fuel problems are electrical, as they say...

[Junkman]

  On 01/11/2016 at 22:01, worldofceri said:

Though I would likely throw myself under a train (or possibly a dark horse) were I suffering the tribulations of the protagonists of this thread, it is nevertheless chock-full of lolz.

 

You just read them in a thread. The real lolz happen when you are in the thick of it.

Because those frequent Mr Beanesque episodes are carefully not reported.

 

 

  On 01/11/2016 at 22:41, spartacus said:

99% of fuel problems are electrical, as they say...

 

100% of all fuel problems are not a sufficient quantity of it getting into the cylinders.

The more fuel and air you manage to get into an engine, the more oompf comes out of it.

[Squire_Dawson]

  Quote

 

I just got the car tuned up

 

Peter, if the engine was tuned whilst idling, the mixture can weakened so that it gives an optimum idle, but the engine isn't doing anything useful then (like pulling under load!). Turn each jet adjuster nut down a flat or two at a time, increase the engine revs to clear the manifold and road test, repeating until you get good performance.

 

Ignition faults tend to be sudden in my experience.

[Junkman]

The car was tuned by the head honcho of the Rover Sanatorium using a Sun tester and gas analyser and was subsequently road tested.

I'd still tell him about it.

[Conrad D. Conelrad]

Today I took the carbs apart and cleaned them out. They were already clean enough, but whatever. I also made sure, a second time, that the fuel lines were clear. 

[Skizzer]

  On 02/11/2016 at 00:13, Junkman said:

The more fuel and air you manage to get into an engine, the louder the bang when you finally get the ignition to spark.

EFA.

 

Good luck!

[steve_earwig]

Lordy It doesn't sound like it's misfiring, just like you're stamping on, and then releasing, the throttle like a loon. Two carbs, both doing the same I guess. Fuel supply? Already eliminated. New fangled throttle linkage? Probably not. Could you fit the conventional dizzy just for porpoises of alimentation?

[DSdriver]

Without bothering to read the whole thread I thought I would tell you that my DS suffered from fuel supply problems that were due to the inner layer of the fuel hose upstream from the pump contracting due to suction from said pump. Hoses looked fine from exterior due to having reinforcing halfway through the rubber. 

The problem showed itself by random inability to get any performance.

[Junkman]

I don't believe it's a fuelling problem.

[DSdriver]

The other one had a problem with the cap of the 123 dizzy.

[Junkman]

I'm with steve_earwig here. I had some newfangled ignition tosh fitted for a while and nothing but problems with it.

I ruefully returned to proper points and condenser and ritually binned that post 1986 tat.

[Asimo]

Rev counter is all over the place because of an ignition fault and not because engine speed is changing. If it has an electronic ignition module, bin it and go back to Mr Kettering's arrangement.

[mat_the_cat]

Agreed with the ignition fault diagnosis - there is no lurching with the indicated engine speed, and I don't think it's even possible for the revs to jump that quickly! I've seen very similar with a failing coil, which may be the easiest thing to check by substitution?

[Conrad D. Conelrad]

So, ignition.

 

 

The spacing between this trigger wheel and its sensor was reason this ignition system didn't work when it was first installed, so that was the first thing I checked. It was fine. The distributor cap, also fine. 

 

© PROFESSIONAL AUTO-ELECTRICIAN

 

I installed a spare coil, and even a new 12v feed just in case the melting fuse box was the problem. 

 

 

Then I fitted a replacement ignition module.

 

The upshot of all this? NO CHANGE. 

 

It's got to be a fuelling problem. Pump only pretending to work? New fuel line collapsing like DSDriver suggested? Either way, it means getting underneath the car again. Ugh.

[Skizzer]

If you ever get to the bottom of this, feel free to pop round and fix the ignition on my XJ-S. I will supply whatever biscuits are your favourite.

 

Sorry, I mean WHEN you get to the bottom of this.

[Conrad D. Conelrad]

Bearing in mind a vital part of my ignition fixing strategy has been "wait until a complete stranger passing by stops and fixes it for me", you're going to need a lot of biscuits. 

[3VOM]

  On 05/11/2016 at 17:40, Conrad D. Conelrad said:

It's got to be a fuelling problem. Pump only pretending to work? New fuel line collapsing like DSDriver suggested? Either way, it means getting underneath the car again. Ugh.

From a previous picture, it looks like there is some old, hardened plastic pipe on there. Can that go funny internally? Other thought - how are the two carbs supplied with fuel? Is it possible for one of them to starve the other? Also, I agree DSDriver's scenario is possible.

[Junkman]

The old hardened plastic pipe is original and the best stuff imaginable. It even survives e85 long term.

If one of the two carbs is starved of fuel, which is something that happens quite frequently when they are run with the original fuel pump,

a very typical and noticable effect is observed, which not the effect experienced here.

[cort16]

Can it not only be a fuel pump issue if the bowls are emptying ? On a carb car the pump is just there to get fuel to to the bowls isn't it, it doesn't require fuel pressure like ego! Is there a way to fill the bowls manually and see if it runs okay until the fuel runs out?

[Junkman]

Does the fuel pump change its sound when the problem occurs?

[Conrad D. Conelrad]

You can't hear it under any circumstance when the car is running. Never could with it mounted at the back. 

 

I do have a spare one which I'm going to swap in next - it's just such a horrible job, being under the car, in the cold, being pressure washed with petrol.