Thread: Help...2L engine backfire with flame and power loss

Sounds to me like your fuel delivery rate is too low to drive on, you're revving the engine in what gathers in the float chamber after some time. I'd remove the fuel line off the carby and run it into a container, check the pump flow rate, and work backwards to the fuel tank until you find the blockage or fault.

Originally Posted by mfc

no luck
ran under own power for 300 meters then the same thing {smaller backfire,,pop realy} then comes to a chugging stop , wont start immediately {10 secs} then starts but stalls out, 30 secs to a minuit and it starts but dies under power, yet will idle and rev freely while stationary.
only other thing that springs to mind is that the air filter oil bowl is of a different year car{has the steel mesh folded onto the upper part, as in you cant get it off. perhaps its cutting off the air

im now bald.....

and correct I think you are....
just drained the sediment bowel {clean} and it wont refill , pump just keeps ticking. I get about 3 mm of fuel in the bottom of it and that's all..
the pump seemed to be ok as its never given more than 3 to 6 clicks on turning the key{6 if its been sitting a few days 2 or 3 if its started each day}
so ill start from sediment filter back to tank, then pump flow rate
{any idea what the pump flow rate should be??}

aint it alwayse the way...start at the wrong end ignition then its fuel

Yep! The story of my life, always starting at the wrong end first.

Now from your description, I assume that you have a SU style diaphragm pump?
If the fuel line obstruction was on the delivery or carby side the pump would stop quickly with pressure in it's body.

With an obstruction or a air leak on the pickup side , the pump wouldn't make pressure and keeps pumping.
.

If you have abnormal fuel pump operation, why did you ignore it? Fuel is important! Without knowing anything about your pump, it should be able to deliver the worst case fuel consumption you can imagine, plus a bit more. So 1 litre per minute would be a figure to start your back-of-the-envelope calulations at.

Don't worry, you're not alone, a friend of mine has an ancient Hiace camper, and in his wisdom he fitted a cheap plastic inline filter to the inlet side of his electric fuel pump. More filters must be better, s'true?? Anyway he used a heavy duty hose clamp to seriously crush the hose inlet of the poor plastic filter and it therefore leaked as much air as a fly screen door in a hurricane. And his fuel pump was HAMMERING LOUDLY but that wasn't worth noting because, you know, he had a Theory he needed to run past me. So I removed the offending filter and it's been good ever since.

So the point is, check that the hose from the tank pickup to the fuel pump inlet is free of dodgy filters, cracks, air leaks etc and then blow some air back into the tank pickup to make sure it is clear. You may need to clean your fuel tank out if it has been sitting around in the damp air for a while. There may even be rust in there and you may need a tank lining product like Red-Kote to seal the inner surface.

"If you have abnormal fuel pump operation, why did you ignore it?"

I didn't I only found out this morning on draining the sediment trap and it didn't refill ,It had been running ok on the clapped out old engine so had been thinking it was an ignition issue{coil condenser timing} blockage from dirt in tank ...also no filter on fuel pickup pipe..
then ill check fuel flow to carby ...

Arthur , blowing back to tank freed a blockage ,so ill drain/clean the tank and try and find some filter for the pickup then check flow at carbie
anyone know who sells red kote? specialists or repco and the likes?

ps bee utey not meening to be snarkie this issue has only been around 4 days

ps authur it will be a nice change to be hanging over the right hand guard not the left

Originally Posted by mfc

then ill check fuel flow to carby ... ----- Arthur , blowing back to tank freed a blockage ,so ill drain/clean the tank and try and find some filter for the pickup then check flow at carbie

Drop a strong magnet inside the tank that will grab most of the loose rust, with the pickup, a fine brass gauze filter is what should be there, then the fuel line pipe goes up to the sediment bowl, things to check there is another flat gauze filter inside the underneath of the filter head and the inside of the fuel tap.

From the sediment filter up to the pump, there is a couple of blockage points in the pump, where the adaptors are fitted to the body, inside there are two flat valves, they can get rubbish under their seats and another gauze filter accessed from the fitting under the pump body. All of that is able to be checked without pulling the pumps diaphragm seal apart.

---- anyone know who sells Redkote? specialists or Repco and the likes?

I would only pull the tank out if the bottom was weeping, but if you need RedKote I found some on eHay, bit on the expensive side though, I am going to try a suggestion that plumbers PCV glue works as well, but I am yet to experiment with this.

ps authur it will be a nice change to be hanging over the right hand guard not the left

Instead of RedKote I used KBS - found it at the paint place I go to when I want paint mixed.

The price (on a litre by litre basis) was approximately the same (around $120 to $130) but what endeared me to KBS is that they have a 'motorcycle' kit which is designed for a smaller tank.

Anyways, it was well under $100 for the kit and, as you end up pouring most of it out and dumping it, the price fit my wallet a lot better. I still got 100% coverage inside the tank.

I couldn't see the sense in buying a product that, after being opened, had a small shelf life as it would only be wasted unless I had several tanks to do at once.

KBS fit my needs perfectly.

good idea re magnet
scince the bung wont budge ive had to syphon/mop out the tank,for a stop gap im going to try and make up a filter out of a brass carbie one.
it looks like the top half of the tank has a powdery white scale {first time its had more than 10 litres in it was Thursday last...no rust to speak of just some sludge. I think as I filled it its come loose .i knew about the punp filter and the fuel trap one but not the other 2 {parts book out} hopefuly scince the carbie one is spotless it didn't get past the fuel trap {when blown out it was blocked}
ill leave the tank coating as its not leaking and dry it out and vacume/blow/magnet it out .....or just perhaps the bolts on the tank are not seized.