Technical Fuel/running issue

[DavePanda4x4]

Morning all,

My '91 panda 4x4 has a bit of a bug. It starts with choke, idles ok and when warm doesn't need any choke or throttle to start again but.... as soon as I touch the throttle it's cutting out!!

I've been working in and around the engine so something might have been knocked or moved but I don't know where to start as haven't had this issue before. I checked all hoses and lead and all are on. One thing that did catch my eye was the fuel filter. It's not filling up see pic. Any help much appreciated.

I'd love to get her running well enough to take to mot soon!

Dave

 

[kolza]

Does it cuts off/ stalls when engine is warm and choke out?

I would look more towards carburetor and more specificaly accelaration pump membrane, pull-down vaccum unit, enrichment circuit, etc.
https://www.fiatforum.com/panda-classic/445069-1988-mk2-fiat-panda-2.html

ps. just seen you photo, make sure that fuel filter is fitted in correct direction -as it does not look like

 

[DavePanda4x4]

Idles forever until you touch throttle, choke in or out. Think a carb rebuild wouldn't be a bad thing but getting it back dialled in again after would be fun

 

[kolza]

Make sure the fuel filter is right direction.

 

[DavePanda4x4]

I'll take a look thanks muchly

 

[Dragon Man]

how about if you very very slowly press the throttle pedal.

my guess is the accelerator jet in the carb is blocked.

the carb will be full of gunk blocking the jet and the small diaphragm pumps inside it.

take the air filter housing off, look down the carb with the engine off and choke flap open make sure you have a good light source.. whack the throttle open and look for a small squirt of fuel that gets injected into the carb by something that looks like a small old tap.

infact, i made a video on it.. here this should help:




also while you are at it, check the vacuum advance actuator on the distributor. check and see that you can pull a vacuum on it.

if the diaphragm inside has perished letting atmosphere though, that can cause hesitation and stalling when the accelerator pedal is pressed.

it could be the two things combined causing the issue.

 

[DavePanda4x4]

Ok so thanks for the tips! I've been out just now and looked down into the carb and yes there the small squirt of fuel when I move the throttle to open. Also the engine cuts when I take the vacuum hose of when it's running. I've not inspected inside the unit yet. The plugs are black when I check them so I guess unburnt fuel. Fuel filter direction checked and correct too. Gotta love old cars!

 

[AndyPanda4x4]

Yes sounds like the issues we had in Italy, pump jet diaphragm as kolza suggests. Located on the rear of the car behind 4 screws.

 

[DavePanda4x4]

Cheers gents

 

[kolza]

and yes there the small squirt of fuel when I move the throttle to open.

Small quirt might be to small actually, 10 full strokes should give between 8 to 12ml of petrol, there is 'power ball valve' behinde the pump membrane. It might be just dirty or stuck.
Have a look through the carb build data from the other thread.

 

[DavePanda4x4]

Will do kolza

 

[DavePanda4x4]

how about if you very very slowly press the throttle pedal.

infact, i made a video on it.. here this should help:

https://www.youtube.com/watch?v=zQlRMc4jB7A&list=PL0117AE2371B69575&index=16

Watched your video, helpful. My fuel filter def doesn't fill like yours, so think there is an issue getting fuel to the engine too.

 

[kolza]

There is brass bolt in carb base next to fuel-in hose.
Undo that ( 14mm ) and have a look on the secondary filter which seat inside.

But it might be weak fuel pump ( unlikely) or air lock in petrol tank.
Try to run car with no petrol cap - no I'm not joking!

 

[DavePanda4x4]

Ok I'll try that. Did just open tank to see if there was airlock somehow but didn't start with it open. I'll check that secondary filter tomorrow. It's a brand new fuel pump...