Help! 94 fzj80 perol/gas. Fuel issue. (1 Viewer)

[dutz]

Hey there,

i have a 94 fzj80 with 300000km on the clock that has an issue when driving it on petrol. At cold start it revs rough(up and down revving) struggles to achieve 1800rpm, sometimes it will stall. After holding the gas pedal down for a few seconds at about 2000rpm, the revs will hold and start dropping slowly as it should and eventually sit at about 550rpm. But it still idles a little rough(not as bad as start up though) and idles a bit lower than when i have it running on lpg. On warm start up if the engine has been off for 5-15 mins it will start fine and idle normally but still lower than when running on lpg.


Now, when i drive it it lacks alot of power! It also takes longer to change into the next gear. It kind of feels like the clutch is slipping but i know it not because it runs perfectly fine on lpg. After driving it for about 20km thats when things get worse. Between 2000rpm and 3000rpm while light acceleration the engine starts choking and theres absolutely no power or response. It feels like it wants to engage but it doesnt unless i push the throttle in almost to its max. Only then when it goes down a gear and the revs are over 3000rpm the choking stops but still lacks in power although revs are over 3000rpm. Once the choking starts i cant accelerate lightly. Only way to stop the choking is applying heavy acceleration. Its like its starving for fuel at the low end of the throttle. If i turn the engine off for about 5-10 minutes and the start it, itll run again for another 20kms before it starts choking again.


Ive changed the fuel pump and it did help a little abit. What i mean by that is before i didnt have to drive far before itll start choking. Changed fuel filter and fuel pressure regulator and still no change.


Has anyone experienced this before or know what i can do next to find the problem. Maybe injectors?


Vehicle is a 1994 fzj80 1fz fe 4.5 auto

Thanks

 

[SmokingRocks]

I would start by getting a gauge on the fuel line to the engine and observing fuel pressure. If the pressure is fin there then I would move between the regulator and injectors and test there. If that's fine then I would probably start looking at the injectors.

Definitely sounds fuel related especially since it runs fine on lpg. I am wondering if the lpg has fowled your injectors or something else.

I am not knowledgeable on the lpg side and what that may do to the injectors so I will let someone else jump in.

 

[dutz]

I would start by getting a gauge on the fuel line to the engine and observing fuel pressure. If the pressure is fin there then I would move between the regulator and injectors and test there. If that's fine then I would probably start looking at the injectors.

Definitely sounds fuel related especially since it runs fine on lpg. I am wondering if the lpg has fowled your injectors or something else.

I am not knowledgeable on the lpg side and what that may do to the injectors so I will let someone else jump in.

I would start by getting a gauge on the fuel line to the engine and observing fuel pressure. If the pressure is fin there then I would move between the regulator and injectors and test there. If that's fine then I would probably start looking at the injectors.

Definitely sounds fuel related especially since it runs fine on lpg. I am wondering if the lpg has fowled your injectors or something else.

I am not knowledgeable on the lpg side and what that may do to the injectors so I will let someone else jump in.

Thanks alot bud! I will check pressures and go from there.

 

[SmokingRocks]

I do know that a byproduct of burning LPG is H2O vapor which can cause corrosion.

I am also starting to wonder if this is a tune issue. It would make sense that pressurized LPG wouldn't need the injectors to pulse for as long to supply the right amount of fuel as the gas would need for a stoich mixture, so if there is not a tune (or it is not working) to revert it to gas then that might explain the starvation.

Has it always done this or is this a new phenomenon? Do you have to make any physical changes to the engine when switching between LPG and petrol?

Again I am just speculating based on my very limited knowledge of LPG / gas switchable engines. I'm tagging someone else in now. Good Luck, I'm interested in seeing how this works out.