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I am going to start a new thread on my problem as I am getting replies on the OPs concern and not mine.
I have a 91 Toy 2 wheel drive pickup with 22re ....
The engine starts and runs 10 seconds only at idle...
I have done MUCH testing...only replaced Main EFI Replay...but have purchased a new COR, not installed as yet....
The fuel pump will NOT run with diag. port B+-Fp jumped...
The fuel pump WILL run when AFM vane is held open and the engine will start, idle and run at high rpm....
I believe the COR is BAD but it test as GOOD....
Recently I did the tests outlined by Scope103 and would like to have some feed back on the results....
To me, a couple of the results seem out of line....
Results from using Scope103 tests for no fuel on startup;
1. across B+ to Fp = 250.4 ohms (which seems high)
2. shorting B+ to Fp at Diag plug results in no start
3. at diag plug B+ get 12.49 volts with key on
4. with key off, at diag plug, get 1.1 ohms to ground from Fp
5. with key on and AVM door open the fuel pump runs
6. checking continuity between FC and E1 get 0.0 ohms
7. with key on at AVM connector, checking for 12 volts to ground, no voltage but there is 19.0 ohms
...with further testing I have discovered that the VSV that controls the fuel pump pressure has failed and, if I am reading my diagram correctly, it would create a vacuum leak directly into the manifold ?
...It is ;Toyota vsv Aisin 90910-12084....I am wondering if the 3 port Aisin VSV on Amazon,(25860-62010 Toyota Vacuum Switching Valve Solenoid VSV) could be used to replace it ....
...something else I found is that the fuel gauge is functioning as it changes as fuel as added...but...if I completely disconnect both sides of the battery, it stays at last level....How is this possible?
1. Jumping the Diag. B+-Fp makes PUMP RUN and truck will start but NOT run above idle for more than 5 seconds.
2. Holding AFM wide open, with air tube in place, truck will start and RUN at idle and at 2000 - 3000rpm for as long as I want but has a very strong smell from exhaust of un-burned fuel.
3.There is also a rough spot from about 1000-1200, a slight miss, maybe from the extra fuel.
4. There is a dry fuel return line but engine runs fine at extended 3000 rpm.
I have run all diagnostic tests on ECU, AFM,TPS,VSV outlined in AllData with passing results.
I am hoping that when I receive my new COR this problem will be solved.
Did you examine the Fuel Pressure Regulator at the rear of the fuel rail? It sounds to me, if there's no fuel in the return line, which is connected to FPR, you have a problem with the FPR. It's supposed to return the unneeded fuel the pump provides to the tank. There should be a constant flow back to the tank from the fuel pressure regulator. It's possible that the fuel smell is due to getting excess fuel in the fuel rail coming out through the injectors, instead of returning to the tank. The VSV controls the pressure, causing a higher pressure in the fuel rail after a heat soak, to help prevent bubbles forming. Once things cool down after the engine has run for a few minutes, it will shut down the higher pressure, causing the FPR to return the excess fuel to the tank via the return line. Event at the higher pressure setting of the FPR, it should still be returning excess fuel to the tank via the return line...
My lengthy way of saying, check the FPR's return line...
Some of your other readings indicate a bad COR.
Pat
With the AFM door open, the engine will run steady at 2-3Krpm making me think the fuel pump is OK ( it's actually less than a year old (as is the tank and fuel filter)...
But the return line is bone dry....and it seems like there should be at least a little dribble fuel there?....
I can pull vacuum on the fuel regulator...but it seems to have a very slow leak...
The VSM and hoses for it tested ok....
I get my new COR in a couple days...so that may change something....
Since no fuel was coming thru the return line, I decided to take off the fuel regulator ( had to remove ERG pipe on back of plenum ) and the reg appears to be blocked as I cannot blow air thru any port, even after applying vacuum to top....
Once I had the reg off, I could see that the threads were the same as my compression gauge ( or very close) so I threaded the hose in and let the pump run for 60 seconds.
I got 700 mls or 24oz. which might be ok...but then I decided to attach my cheap compression gauge to the same line....
...and got 0 pressure....
I am pretty sure I should have gotten something ?....
I am going to take the plugs out and turn it over in case I was filling up the cylinders....
2. with only AFM door held open....engine will NOT run
Was the air tube from the AFM to the Throttle Body in place, and sealed properly?
With Fp to B+ shorted, or jumpered, check the positive lead at the fuel pump for battery voltage, give or take about a half a volt. WITH the key in the START position, but the clutch NOT depressed. Honestly, you should be able to hear the the fuel pump run, and not need to check the voltage. Then with the key in the ON position, clutch not depressed. Can you hear the fuel pump run? Make sure the COR is installed properly.
Same with the AFM door open. Again, key in START, clutch NOT depressed. And key in ON, clutch not depressed. Can you hear the fuel pump run? Again, COR installed properly.
Then check with both conditions met.
Then check the voltage at about 1/2 way between the battery and the fuel pump, with one of the two conditions met, then the other. If it's good, go back about 1/2 the remaining length to the fuel pump. If it's bad, go towards the battery and check the voltage. Splitting the circuit this way will find the problem in no time. It's the method electricians and electronics techs use. Keep making the circuit smaller and smaller by halves, and you'll have the problem solved before you realize it.
Always ensure your meter has a good ground connection before checking any point for voltage. If you need to, make a LONG lead for you meter, and leave it connected to battery negative terminal. Ensure that the fuel hanger, and so forth, have good ground connections to the battery. It's known for corrosion buildup.
As an ongoing test, I started the engine with the AFM held completely open and the slowly moved the vane back towards 0 and fuel pump shut off position.
I could see that the engine began to falter at the third (3rd) shaped black triangle in the AFM.
I did all checks of Ohms at the AFM connector, which were correct by the FSM (an other YotaTech members)...
I also did checks of continuity of wiring between AFM plug and Computer, which did not indicate voltage loss or short....
I am wondering what exactly is happening at this 3rd black triangle shaped point in the resistance strip?...
b. what information is being passed to the computer ?
c. what other components are involved?
Thanks for any guesses....
These are pure guesses. I don't have access to that schematic. But from what I can tell, I would guess the wire circled in red, goes to ground, to allow the relay to energize.
Black-red at the top, I have no clue.
Symbol circled in yellow is a connection point. Mostly used to reference that point in the information concerning the schematic.
Yellow circle area with C1 in a box is a connector, the pin number for the wire is outside the box.
I can't find the symbol in the red circle in my EWD for my car (89 toyota). My guess is the B-R off the starter relay joins back up with the B-R at the top...
Ground symbol is usually three dashes stacked with long dash on top and the other two shorter in length.
...So...after ALL of my testing I finally got around to changing the fuel pump....
...I had resisted doing so because it seemed to be functioning at certain times and I thought, since the pump was only a year old, it may have been wiring related....
...As soon as I took the pump out I could see the problem....The short piece of rubber fuel line that connects the pump to the outgoing metal line had Burst !....
...I have never witnessed this before....and I am wondering if the line supplied by the pump manufacture was bad or if something in the pump could have failed to produce such a outcome ?....
...I ask if the pump could have been the cause as the port (circled in image) appears to have a loose part....
...I am not going to trust this pump and install a new one (from a different manufacturer)....
The fact that it burst may be connected to one of your initial posts on this thread about the FPU valve not functioning. If the fpu valve is always vented to atmosphere the fuel pressure will remain maxed out which is above 40 psi (44 If I remember). When the fpu valve is switched, it gets vacuum from the plenum to raise the needle in the fp regulator which drops fuel pressure to 30ish psi ( I'm remembering 32psi). The fpu valve gets its signal during startup from ecu when ecu is getting a hot reading from coolant temp probe to prevent vapor lock during hot restart by temporarily increasing pressure. I'm sorry but I don't remember if the fpu valve is normally switched to plenum or normally open. I do know that if you remove the fpr vacuum hose from the fpu valve and stick it directly to the plenum, it will not give issues unless it's hot outside.
Last edited by Dernation; Mar 14, 2024 at 02:42 PM.
...Thanks for the reply...
....That is an interesting thought....
...I originally put it's failure down to Ethanol and a cheap hose provided by the manufacturer of the last fuel pump....
...but , as you point out, the VSV was not functioning ( since replaced)...
...I am just finishing the install of a new fuel pump ( I opted for one of the newer smaller ones this time and had a lot of re-wiring and mounting issues to solve) ...and I will certainly re-check the functioning of the FPU....
...While apart...I did also discover that the return line from the charcoal canister is plugged....but I'm not sure if that would be able to create extra pressure back at the pump location....
...I am pretty sure if the pump ever fails again on this truck, I am going to install an inline one ...I see there are some design now that can actually suck right thru an old pump left in place in the tank....
When I was recently replacing my fuel pump and found the short 4" piece of in tank line had ruptured, I ran some fuel thru the return line to the new pump...
Immediately I could see that the fuel was eating the R9 rated line, turning it into a black mush ....
Now, I am curious as to whether the Gas is very Bad...or is the Fuel line Not as Rated?....
...Thanks for the reply...
....That is an interesting thought....
...I originally put it's failure down to Ethanol and a cheap hose provided by the manufacturer of the last fuel pump....
...but , as you point out, the VSV was not functioning ( since replaced)...
...I am just finishing the install of a new fuel pump ( I opted for one of the newer smaller ones this time and had a lot of re-wiring and mounting issues to solve) ...and I will certainly re-check the functioning of the FPU....
...While apart...I did also discover that the return line from the charcoal canister is plugged....but I'm not sure if that would be able to create extra pressure back at the pump location....
...I am pretty sure if the pump ever fails again on this truck, I am going to install an inline one ...I see there are some design now that can actually suck right thru an old pump left in place in the tank....
Regarding the charcoal canister, I'm not sure which line you are referring to as plugged. The line I call the tank vent line, goes from the tank to the charcoal canister. It's job is to give the expanding gasoline fumes somewhere to go that does not vent to atmosphere (EPA regulations). The other line is a vacuum line that goes from the can to the plenum that allows the fumes in the can to be burnt in the engine. If it's plugged, you could have over twice atmospheric pressure inside the tank and parts of the fuel system. The above post also shows what happens when line that's not rated for the liquid it's carrying gets eaten up. The pic you posted looks like a blow out from a damaged hose. Gotta run how this helps!
Feb 15, 2024 | 05:15 PM
Need interpretation of fuel system test results
22r3 Truck Runs with AFM held open
