Series III surging

[mearstrae]

Pick up a hand vacuum pump with a gauge. (It can also be useful for bleeding brakes.) Attach to the vacuum port on the distributor and pump until the advance moves it's full travel, the gauge will show at what engine vacuum it will move. If you try this with the engine running, put a golf tee in the line running to the carb. You may also want to check the engine vacuum to be sure it is pulling enough to operate the vacuum advance.

'99 Disco II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S

[erik88lr]

This is not a slam on RN as I buy a pile of parts from them, but their aftermarket fuel pumps are not great. I have been through several that just won't deliver enough fuel to keep the truck running at speed……pretty much exactly like what you all describe.

Find a nice original AC fuel pump and you should be good. There are several vendors state side that you should be able to pick one up from.

I ordered one last week from D.A.P. Enterprises, but it turned out to be a rebuilt pump identical to the ones our esteemed host sells, and it works identically too: 0 to ½ psi.
If you would send me a PM with the name of one of the vendors selling new original AC fuel pumps I'd appreciate it.

The other possibility is that the last few pumps I've put on are fine, but I'm asking too much of them by having a fuel filter and electric pump inline for them to have to draw through....

[raleighrover]

UPDATE: looks like the culprit was the fuel pump after all; put a new one on, replaced the inline filters and it's running like a champ again. Planning on getting a rebuild kit for the old pump - looks like the original AC one.

Thanks for the advice and guidance; I appreciate it.

[REDrum]

My SIII has been running really well, but all of a sudden has started "surging" when I get in fourth - around 40mph. It accelerates and pulls strongly (for the 2.25) through 1st, 2nd and 3rd, but when I get into fourth it starts to surge or lurch as I accelerate, and I need to back off.

Quick question for you... Is the "surging" you describe like someone pulled on the throttle cable type surge or is it more like a bucking where someone is rapidly pushing down on and letting off on throttle cable? I.e. lots of fuel then no fuel every second)

Glad you solved you problem I may have similar

Thnx

[raleighrover]

The second....pushing down then letting up...bucking would have been a better description.

Quick question for you... Is the "surging" you describe like someone pulled on the throttle cable type surge or is it more like a bucking where someone is rapidly pushing down on and letting off on throttle cable? I.e. lots of fuel then no fuel every second)

Glad you solved you problem I may have similar

Thnx

[REDrum]

The second....pushing down then letting up...bucking would have been a better description.

Thanks, that helps!

[raleighrover]

Update: I replaced the original fuel pump with a new aftermarket one. The truck ran well for a bit, but then the new pump started leaking gas into the crankcase. I replaced it with another new aftermarket pump (and changed the oil!), and it's been working pretty well. When cold, the truck starts great and runs really smoothly. However, when the engine is warm it's much harder to start. It almost acts like it's flooded - I need to give it a lot of throttle to get it to fire, then it will only run on a few cylinders for a few seconds before it smoothes out and runs well.

It used to start just fine when warm or cold, so not sure what's going on. Could the fuel pump affect the way it starts when warm? Any other ideas? the pumps are the only thing that has changed.

[erik88lr]

Update: I replaced the original fuel pump with a new aftermarket one. The truck ran well for a bit, but then the new pump started leaking gas into the crankcase. I replaced it with another new aftermarket pump (and changed the oil!), and it's been working pretty well. When cold, the truck starts great and runs really smoothly. However, when the engine is warm it's much harder to start. It almost acts like it's flooded - I need to give it a lot of throttle to get it to fire, then it will only run on a few cylinders for a few seconds before it smoothes out and runs well.

It used to start just fine when warm or cold, so not sure what's going on. Could the fuel pump affect the way it starts when warm? Any other ideas? the pumps are the only thing that has changed.

Could be that it is literally flooded. I recently had to replace my Zenith carb float because one of the two chambers was half full of fuel.
Another factor could be vapor lock caused by the ethanol in the fuel sold these days. You might true a tank full of pure gasoline. See https://www.buyrealgas.com/