slight miss

[Ranman]

I have a 1986 2.9l Ranger. Recently, I inadvertently put diesel fuel in to my gas tank. That being said, I had the tank pumped out. Replaced fuel filter, # 6 injector, new wires and plugs. It runs , but has a slight miss, and has no power. I replaced the fuel pump about two years ago. I have been racking my brain trying to figure out the problem. Just a few days ago I replaced the fuel filter again, but it did not resolve the problem. How can I check the fuel pump ( the one on the frame rail) to see if it is working properly. Also the small fuel line that goes from the fuel pressure regulator to the intake manifold vacuum port broke. I is plastic and I put it back together with a small vacuum line and clamps. Any input would be greatly appreciated. Thank you.

 

[bmerr98]

Check the basics. Recheck plugs gaps and plug wire connections. I don't think the diesel fuel should hurt you too much since you pumped it out and (presumably) refilled with gasoline. I may be wrong, but any diesel left should have mixed with the fresh gas at a low enough ratio to negate any ill effects. You've changed the fuel filter. Checking for proper air flow and spark plug gap would be the next logical steps. Your patched fuel line might be ok as long as it isn't restricting flow or leaking. A pressure gage would show what kind of fuel pressure your pump is giving you.

Basics first though.

 

[Ranman]

Thank you I will do that. I even cleaned the throttle body. I found that the computer is under the right kick panel. Is the any other place I code check with a code reader, maybe it would help me sort this out.

 

[bmerr98]

My reasoning for the basics is that I went for, heck I forget how long with a miss under acceleration that smoothed out at higher rpms, convinced that it was some complicated thing that would puzzle trained Ford factory techs. It was bad spark plug gaps. Just trying to spare you the stupid feeling and the aggravation over time. Fuel, air, spark. Of course cleaning sensors and such can help too.

 

[Ranman]

At first light in am I will pull them and recheck gap. I hope it is something that simple. Thanks again.

 

[RonD]

Also the small fuel line that goes from the fuel pressure regulator to the intake manifold vacuum port broke.

The there is no fuel line connection between FPR and intake manifold.
Inside the FPR is a diaphragm, the vacuum in the intake pulls it open to allow fuel to return to gas tank, vacuum is highest at low RPM, so diaphragm opens more at idle and closes at high RPM.
This keeps fuel pressure between 30 and 40 psi at the fuel rail.

If this is not working then you could be sucking fuel up that vacuum line, a bad thing, or your fuel pressure is not between 30-40 psi so computer's fuel mix will be off.
If there is a gas smell in the FPR vacuum line or gas itself then replace FPR, it is flooding the engine and the closest cylinder to the vacuum manifold is getting most of the fuel so missing.

Best way to test a fuel pump is to use a fuel pressure gauge at the fuel rail.
Tests are:
engine off key on
engine running at idle
engine running at 3,000 rpm
engine at idle, FPR vacuum line unhooked, this tests the FPR

Then after the above, engine off key off, 10 minute wait, test pressure; this tests if system has a leak, it should hold pressure

 

[ab_slack]

The there is no fuel line connection between Tests are:
engine off key on
engine running at idle
engine running at 3,000 rpm
engine at idle, FPR vacuum line unhooked, this tests the FPR

Then after the above, engine off key off, 10 minute wait, test pressure; this tests if system has a leak, it should hold pressure

What pressure would be expected at each of the conditions?

 

[Ranman]

Still Checking miss

I appreciate the response regarding the miss issue. I have recently replaced the FPR. Upon doing so I Noticed the O ring was leaking at the fuel rail, I took it back and received a new one. After installation, no leaks. I realize now that the little plastic hose that went from the FPR to intake was a small vacuum line. I put it back together with a piece of small vacuum hose when it initially broke. I will replace it today with a new piece. How does the little cap that covers the Schroeder valve on the fuel rail come off, does it unscrew or just pull off? I'm hoping one of the auto parts stores has a fuel pressure guage that they will loan out. If the pressure from the FPR is low how do you increase it? Thanks for all the info and advice.

 

[RonD]

Should just unscrew like the tire valve cap

 

[Ranman]

Thank You.

 

[SenorNoob]

Be aware that parts store tool rentals may not be accurate. I had a similar problem when my o2 sensor was wired backwards. The parts store gauge showed 0 PSI. Couldn't have been right when I drove the truck to the store and tested it in the parking lot.