Club 80-90 Forums

Hello.

I appear to have a flat spot when accelerating in all gears. It is only very slight and I just rev past it which is fine. However being a little OCD it is beginning to bug me.

Does anyone know how to correct it or should I just leave well alone as the Smurf runs like a dream.

what carb what engine?

Oh yeah it does help if I put that stuff on here.

It a 1.9 water-cooled engine with a pierburg 2E3 carb.

As issue it's not a major problem it's just a little annoying.

What rpm does the flat spot occur?

no guesswork now

Dave307 wrote:Hello.

I appear to have a flat spot when accelerating in all gears. It is only very slight and I just rev past it which is fine. However being a little OCD it is beginning to bug me.

Does anyone know how to correct it or should I just leave well alone as the Smurf runs like a dream.

Ok a flat spot can be caused by several things, two that spring to mind are....
1/. The accelerator pump diaphragm leaking and not squirting the full amount of fuel in to the transfer jet, thus causing a hesitation or a slight faltering depending on the severity.

2/. Advance mechanism fault.

What Kev said ^^^^^^^
Vacuum advance unit holed (suck down the pipe to check for a leak).

Dribble instead of spray (on the accelerator pump)

Martin

Would third that.

I had a sluggish van recently and it was down to a worn rotor arm and dizzy cap. Also old ignition leads can break down

The flat-spot could be another symptom of you running out of petrol & and crap getting into the carb.

The flat spot was there prior to the petrol FAIL I had recently.

I have no idea about the revs as I have no rev counter. It is however low ie just as I start to accelerate.

It only seems to do it in 2nd n 3rd gear.

As I said it is only really noticable at low speed and it's not bad it's almost like a hesitation. Then push the accelerator a little further and it pulls straight off.

I will check the above and see if that works.

I've had this with same engine/carb, changed carb for a re-built one and not much difference. Have a good S/h dizzy with known good vacuum on it to see if that makes a difference. I suspect that either my mechanical advance and/or vac unit are worn . Let us know how you get on. When my new Dis' comes i'll see if it works and suggest you do or do not do same!

Is the throttle cable adjusted properly?

BOXY wrote:Is the throttle cable adjusted properly?

I did wonder about this.

The other thing I was gonna ask was could it just be idleing to low.
I'm gonna have a look at it at the weekend.
The van is still new to me so was thinking that it could probably do with a damn good service ie sparks leads dizzy filters etc. I know the bloke who owned it prior to me did oil and water recently but had done the rest and the van was sat for a bit.

Will keep you posted on what I discover.
As i said I will do as I always do and work through each idea and see if it works.

Ok. I messed about with it and cant sort it. Have got the backfiring back that I had after the petrol run out fail o had recently. I've run my mechanic and I'm gonna bite the bullet and get him to sort it for me.

I have checked the fuel filter again and it is again full of cr*p. It's only done about 200 miles since I changed it.
What i was wondering was how easy is it to flush the petrol tank as I think it is full of cr*p at the bottom which isn't helping. Woul I be better off changing the tank or just flushing it.

My mechanic has said he will sort the rest but said if I wanted the tank flushed or swapped I should do this first otherwise him sorting the carb etc will be pointless as it will just get full up again.

He has offered to swap tank or flush but thought if it is easy I'll do it myself first to save the cost as money is not easy to come by.

Advice PLLLEEEAAASSSEEE.

changing the petrol tank isnt that hard really, just remove it systematically and put it back without having bits left over. however in my experience the biggest problem is dealing with the bits that break when you are doing it.

usually the bolts holding up the supports will shear off but you can easily drill a new hole and put in a new nut and bolt.
the screws which hold in the petrol cap sometimes are a bit of a pain. there is also a rubber connecting piece behind the petrol cap connecting it to the filler pipe which is often corroded cause all the crud sticks around it, this usually leads to water getting into the tank when the van gets a good wash, it may be that this is where the crap is getting in rather than the tank being rusty.
the breather hoses will no doubt be corroded and even if they arent you may as well replace them whilst the tank is out.

with the symptoms you have my first port of call would be to clean out the carb and get the tank sorted, sound like it needs doing anyway even if it doesnt fully sort it