Engine losing power under load

steveod

I have a 1984 1.9 carb engine in my camper and it has started to backfire a small bit when the engine under load.

Also, I might be driving along and suddenly the engine will pull as if the brakes are on and lose revs. I can get the revs back up but I have to ride the clutch.

The engine idles ok but sounds a bit erratic, but when I put my foot on the gas, it pops and backfires

I've changed the fuel and air filters and the sparks so I'm guessing it's not the delivery into the carb.

I'm trying to eliminate the problem by a process of elimination, but truble is, I don't really know what to take a look at next.

I'm guessing it's a fuel delivery problem, but only when engine under load.

Anyone any ideas?

the merchant

Does that engine have ignition points? If so you could change them and adjust ignition timing if required.

Nissan doctor

Checking the spark is the first POC(points, leads etc), then your into checking the operation of the carb, checking the timing and checking valve clearances..

steveod

Thanks I've narrowed it down to fuel delivery problem in the carb.

Checking the jets next

CJhaughey

What engine is it?
Is it by chance running a Pierburg Carb? some of these give trouble with carb icing.

steveod

It is a Pierburg carb, but I don't think the problem is icing, as the problem has been running for a while.

The problem occurs only when I floor the gas. The carb pops and splutters and eventually catches up. I have checked the auto choke at that's working fine so I think its a fuel jet blockage. If it's not that, I'm stumped.

Will keep you updated.

SouperComputer

So it's running lean then? Acceleration enrichment/pump jet not working maybe?
Noticed you said it happens when you floor it, if it's a distributor system that has vacuum controlled advance there could be an issue there as well.

CJhaughey

It doesn't have to be that cold to ice up, on the 2E carbs they have a small black rubber heater element that sits against the venturi. If this fails the carb will ice up even above freezing conditions.
Vacuum hoses also leak and give trouble, fill a spray bottle with soapy water and spray it around the hoses
I had a problem with a MK2 Golf 1.6 Pierburg and I ended up replacing it with a Weber 32/34 DTML replacement. They turn up on ebay pretty regular.
The Pierburgs aren't great tbh

steveod

I've been trying to check the vacuum by spraying Carb Cleaner all over the place when the carb lid is closed, but haven't noticed any change in engine sound so am guessing its a jetting problem.

I also took the lid off the carb and hooked the choke open with a piece of galvaised wire and floored it - same thing, splutter/backfire so it's not an air supply problem. Can't see what's going on cos am working on my own, but need to check down the venturi and pump gas at same time to see what happens.

Found out that there are 2 filters on a 2E. The big one and a small one which needs to be taken off with a screw remover!? Might check out the Weber if no joy