coltonstewart

Hey guys, Ive been posting in here lately about the same truck (92 3.0 pickup) but different issues, as Im slowly narrowing down the cause of my steady misfire, rough idle, unburnt fuel issue. As I run the fuel pump the return line is connected to the FPR by a clear hose. During the first 10 - 15 seconds the fuel appears to have no air bubbles but then consistently produces air bubbles in the fuel to the return hose. Im sure the hose has a complete seal on the FPR. I would assume that you want no air at all in your fuel but maybe this looks normal to you guys? I imagine if air bubbles were hitting the injectors they would sputter rather than spray.. What do you guys think? Have you seen this occur in Toyotas before?

Video link:
https://youtu.be/J39ZhBvaohw

Terrys87

iTrader: (1)

I have not seen air like you are posting. If it were me, I would start checking from the tank to the fuel rail and see if I had any issues there.

millball

In a fuel injection setup like yours, where there is a high pressure pump in the fuel tank that pressurises the entire fuel supply side lines to relatively high pressure, there should'nt ordinarily be any bubbles in the fuel stream.

I'd look to some sort of fault in the fuel pump suction side that could induce air into the fuel stream before the pump pressurises it.

Co_94_PU

iTrader: (-1)

It's agitation in the tank causing this. Proof, run your return into a 5gallon bucket and it will not happen. The clue is how long it takes to begin happening.

The pump inlet is submerged, the pump mechanism is also. For air to enter anywhere up stream once it is pressurized it would have to be at an equal pressure as the fluid. So it has to happen at the pressurization stage.
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at any rate if there was air being pumped along with the fluid it will pass right thru the injector in its compressed form and not be displacing any substantial amount of fuel.

PS probably not really good for the pump to feed it so much air