I went back to test the FC and E1 terminals on the air flow unit because I just wasn't convinced I had done it correctly. Today, with door closed, my ohm meter read '1.' When pushed open (guessing) about 1/8 inch, it still read '1.' I had to push it open about (guessing) 1/4 inch before the meter jumped for a millisecond to about '11' and then settled at around 1.1?

Based on what I wrote above, does anyone think I need to explore replacing the air flow unit?

 

Anybody?

Trying to work through the laundry list of possibilities I posted two posts ago, but was wondering about the air flow test in the last post. Any help is appreciated.

 

As long as this was 1.36k ohms (1,360 ohms) you are ok.

No, I don't see anything wrong with the VAF.

^ I would go through these checks. All of them could be the issue you are having and are related to the code 25.

Check the E1 circuit with your multimeter in the voltage funtion by probing the +B and E1 terminal in the DLC1. You should have battery voltage or very close to battery voltage at these terminals when the ignition is on.

Do a voltage drop test of the E1 circuit by putting the red lead on the E1 terminal in the DLC1 and the black lead on the battery ground post. Your multimeter should show almost 0 volts. If it reads any significant voltage, you have a bad splice, or loose E1 ground connection.

You said you didn't detect anything in the fuel hose. This might be something to check into. If you use the ammeter function of your multimeter to connect +B and FP terminals like you did with the paper clip, you should read about 4 amps or so with the ignition on. You should also hear the fuel pump. Only a fuel pressure test with a gauge will give you a definitive answer, but I assume you don't have a fuel pressure gauge. I don't know if the Centech multimeter has an ammeter function. Make sure to pull the probes out of the ammeter socket on the multimeter when you are done so you don't accidently short something when doing other tests.

Check for injector pulse by using a 194 type bulb with the wires bent to fit into the injector connector. The bulb should flash when you crank the engine.

Does the engine attempt to start when spraying starting fluid into the intake through a vacuum line?

The above are simple checks that I can think of to help narrow the problem down, and shouldn't take more than a few minutes.

 

Rusty, thank you for your instructions; I am just now getting to these. Meanwhile, the truck sits in the garage.

1) You asked me to check E1 and B+. I turned my Centech on 20 DCV and it read about 12.xx volts with ignition on.

2) Voltage drop: red lead on E1 terminal and black on battery ground post. I turned ignition on and it read '0.'

3) Ammeter function: (uploaded an image of my Centech). To try the ammeter function, do I move the 'red' input from voltmA to the 10ADC input?

 

By the way, you also asked if the engine attempt to start when I spray starting fluid into the intake through a vacuum line. I did not know which vacuum line to remove, so I removed the air intake hose and sprayed the starting fluid for three seconds right into the intake mouth. The first time it started, but still did so roughly. Now the truck doesn't start at all, even when spraying this fluid into the intake. I haven't started the truck, though, in about two weeks (life got in the way).

I keep wondering if this is a fuel pump problem. I replaced the fuel filter, but that did no good. I replaced the ECT valve (way back by the firewall). That did no good. And, as previously mentioned, the VAFM seemed to test well.

I will try to do the injector/194 bulb test later.

 

i would triple check and make sure you got the plug wires hooked up correctly. may have crossed a few. easy to do man.

 

Correct. The red lead goes to the 10amps DC socket to use the ammeter function.

Just make sure to hook up the intake hose before you start it. The fuel pump needs a signal from the VAF to run. If you leave it unhooked the VAF plate will not open and the fuel pump will only run when you have the ignition in the start position.

You very well could have a fuel delivery issue. A fuel pressure gauge is a good diagnostic tool to verify this, you will have to decide if you want to invest in one. Seeing how many amps the fuel pump is drawing and checking for injector pulse will help point you in the right direction.

 

Old: Thanks for the tip; plug wires are all connected securely to their appropriate firing position.

Rusty: I test the B+ and FP on the ammeter with the ignition on; it read -3.95. It actually had the minus in there. I heard the fuel pump.

Regarding spraying injector fluid, since I need to leave the VAFM hose attached to the throttle body, can I remove the PCV connection on top of the air hose and spray the fluid into there and then try cranking? If I need to try the vacuum hoses, which of the four that lead into the top of the throttle body should I try.

And, finally, can I test fuel pressure with the truck not running? I can't even seem to get it to stay started now. It cranks but never really 'catches' and fires up.

 

Oh, yeah, forgot to ask, where is the fuel injector connector? (asked sheepishly)

 

The connectors for the fuel injectors are right on the injectors themselves. They are under the air intake chamber in the 3vze so they might not be accessible with the intake chamber attached. I don't have a 3vze, so I am not sure if any are accessible without removing the intake chamber.

 

Rusty: I rented a fuel pressure test gauge from O'Reillys. After hooking up the gauge, I jumped the B+ and FP circuits and switched on the key. I heard the fuel pump and the gauge, even after about a minute, never got above about 5 psi. I have to assume I hooked up everything correctly.

I've already replaced the fuel filter. Can I safely assume I need to order a new fuel pump? The vehicle has 212K miles. I bought it from someone who bought it from the original owner, so I have no idea if the pump has ever been changed.

I am thinking of ordering the following from Rock Auto: DENSO Part # 9500100 Pump & Strainer Set.

Thoughts on whether this is likely the fuel pump and thoughts on the Denso?

 

Assuming you hooked up everything correctly, your test shows you likely need a new pump. 38-44 psi is specified fuel pressure. I would eliminate the pressure regulator by following the procedure here...
http://personal.utulsa.edu/~nathan-buchanan/93fsm/engine/87fuelpump.pdf

Edit to add: after looking at the procedure in the link, it looks like the engine must be running to check the regulator. If it were me, I would just go ahead and replace the pump. That is 97.326% likely to be the problem at this point.

The Denso is a good fuel pump. That is the brand I would buy if I were fuel pump shopping.

 

Rusty, et. al.

Update: I FINALLY got time to install a new Denso pump. Filled it with a little gas (about two gallons) and started. Although it did better than it was - it started and I was able to press the gas pedal to keep it from dying, which didn't work before - it still ran extremely rough.

As a reminder, I have changed the fuel filter, too. In an effort to read about everything I can to determine what else I might check, I saw something about the throttle position sensor.

Need suggestions on what to try next. Thoughts?

 

BUMP!!

After changing out the fuel pump, I rented a fuel pressure gauge from Autozone. New pump checked out fine. So, I began suspecting bad gas. I drained what gas was in the tank and put in a couple of gallons of new fuel. It ran poorly at first but very slightly seemed to get better.

However, it still 'clatters' loudly and I have to keep a little pressure on the gas pedal to keep RPMs at about 1500. I need help! Any ideas on what to do here? Would the vehicle still run if the timing belt had broken? Thoughts? Suggestions?

 

Can you hear me now? Surely, this is not a lost cause . . .

BUMP

 

If the belt was broken it would not start. It would eventually bind up at the bottom and possibly not even allow it to turn over.

These motors do not like vacuum leaks. All air hose connections good?

I had to edit this. I was thinking it was the 22re and got confused about another thread. I don't know the 3.0 but maybe this will bump you to someone who can help.

 

Thank you, Terrys87. I will make a special effort to check those vacuum lines, but it appears they are all good.

Just to recap because this has been a long thread: I bought the truck last year. It ran well. Just before this all happened, it started to run a little rough on cold startup, but ran decently well thereafter. One day on an errand, the power seemed to just give out. I could still drive it, but it was staggering. Finally, I had to pull over. A friend towed me home.

So, I did the simple things like changing the plugs, wires, distributor cap. No help. With the help of Rusty, et. al., I tested the VAFM and other things. In testing the fuel pump, I realized it was not providing pressure. I changed it. Well, this allowed it to start whereas before it would not.

At that point I suspected bad gas. Drained the little I had in the tank and put a couple gallons of fresh gas in. The truck starts now but it is still very rough. Nothing you could drive on. I may try to run it rough for a bit longer to ensure the bad gas, if any, is out of the fuel line. Oh, and it has a new fuel in-line fuel filter.

The one thing is: I noticed when I was on that errand and the truck seemed to 'lose power,' that the truck also started a 'clatter.' Even now, as I rev the engine to 1,500 RPM to keep the vehicle running I noticed the clatter - even more so. I don't know enough to know what that is, but I think that might be a clue.

Any help is appreciated.

 

Have you done a compression test? If not, that should be high on your list going forward. You might have a valve problem.

 

Yah, was thinking the same thing. It's not to difficult to do the pressure test.

Otherwise, I didn't see you say anything about checking all your vac hoses very carefully. (Sorry, I didn't read every post though) do that as suggested earlier.

When you check your spark, is it a nice consistent spark? I had an electrical issue which caused a very inconsistent spark and cost me lots of power and MPG's.

 

Thanks RJR and Gevo. I will rent a compression gauge from Autozone this weekend and report back. I could possibly try to test the timing but am not sure I can keep it running well enough to do that.