I have an '89 Ford Ranger, 6cyl 2.9L. When I give it gas and try to accelerate, it boggs down, has little power, and then backfires through the intake. The codes that I am getting are 77 and 74, Operator error on balance test and brake. No help there. I did a fuel pressure test and got 35 psi and have also been able to rule out the pressure regulator with a vacuum pump. I disconnected one sensor at a time and no improvements. My #4 cylinder pressure is down to 50 psi and a wet test shows that it is the piston ring. The cylinders are out of balance when spark plug wires are removed ona at a tim, but could that be the problem? If you could give me some advice, I'd be really stoked... Thanks....WoodstockAz

 

I'm going to guess you have a burnt valve, but just to be sure,
what is the compression in the rest of the cylinders?? Another possibility is a sloppy/jumped timing chain, is your ignition timing
anywhere near correct?? Spout removed remember...

 

Thanks for the response.....my other cyls are about 78-85psi, and a wet test on cyl 4 bumped pressure up to 65psi. I checked the timing yeaturday with the spout removed and the pointer was right on the mark which I assume is correct since there is no scale or degree markers. I keep going back to my fuel pressure though because it is so curious. Little to no pressure with ignition ON, then 36psi while running and only a 1 second increase when I remove vacuum from the regulator....what do you think?

 

You should have a scale with degrees markings on the harmonic balancer. There's a line for TDC, then smaller lines and markings for various degrees up to around 30 or so, as I recall. You may have clean up things up real good to find the marks, and you may want to mark the 10 degree line with white-out or a grease pencil or something. Makes it a lot easier to see with the timing light.

 

Colorado Springs....Grew up there on Brisbane Dr................There are two white marks on the balancer, I assume one is TDC and one is 10* BTDC. No writing on either. The timing light shows that I'm lined up with one of the lines. One guy is telling me that I might have a sticky valve......What do you think? I'm thinking of disconnecting the spark and fuel injector from one cyl at a time to try and get rid of the backfire.....that might tell me what cyl is backfiring. I'm still thinking that my fuel pressures are a little screwey though.

 

Ok I'm back.....the timing is exactly 10* BTDC. I'm still stumped???? I really don't want to start replacing sensors and the fuel pump to see which works. I already replaced the fuel filter. One curious thing............idle is good, if I slowly open the throttle, no problem,,,,,,,If I open the throttle quickly= boggs down like it is not getting enough fuel, then eventually backfires through intake. Could it be TPS, MAP, MAF, O2. which one is most likely.??????

 

I checked my Haynes manual when I got home, and they claimed that none of the cylinders should be below 100 psi in a compression test, and they should be within 25% of each other. I almost hate to say it, but you might need to get a new (rebuilt) engine in that Ranger.

 

Ya I know I need a new engine, but I need to work first and I'd really like to get this thing chugging down the road for a little while. I appreciate your effort though. Hey Mrshorty I just got some new info that I asked another guy about. Maybe you could read it and let me know what you think........ I checked fuel pressure and got the following: No pressure Key On, Engine Off; between 20-28 psi with the engine running; no change with the fuel pressure regulator vacume removed; the pressure remains fairly constant at 20-28 psi once the engine is stopped for at least a few minutes. I put on a new fuel filter. The timing was TDC and I reset it to 10* BTDC where it belongs. The codes that I got are 11 or system pass whith the Key On Engine Off and 13,74, 77 with the engine running test. 13=cannot control RPM during low RPM test. 74=Brake switch is open 77=Operator error during dynamic response test or cylinder balance test. I don't know why it would not be able to control the RPMs during a self test or why there was an operator error. Do you think the fuel pump could cause this problem if it was low? Any suggestions as to my next course of action would be appreciated......Thanks

 

Code 13 could be caused by a dirty or bad IAC valve, bad electrical connections to IAC valve, or, for some reason, the computer isn't getting a proper RPM signal. Most likely a problem with the IAC.
74 and 77 are set during the KOER test if you fail to press the brake after the computer outputs the engine ID code or if you fail to perform the "goose" test when the goose test pulse is received. If you performed the test properly, then there is a problem with the brake on off switch (74) and/or the TPS circuit (77)
Those fuel pressures look low, what happened to the 35 psi you were getting earlier? Do the '89's have one or two filters? My '87 has two.

 

Mr. Shorty, I have an 87 also where is the second filter located at and what is the part number. I would appreciate the help. My truck is having a loss of power problem and as of right now I don't think my low pressure fuel pump is working.

 

On mine, there's a filter on the frame rail between the tank and the high pressure pump. It contains (I've heard that sometimes it doesn't) a filter element that you replace by unscrewing the housing. The high pressure filter lies in the frame rail as well, downstream from the high pressure pump.

 

No there's only 1 filter on the '89. The 35 that I used to get is gone.......it's lower now which leads me to believe that the pump is bad. I'm thinking of just replacing it tonight and see what happens.....hope it works you know.

 

Let us know how it turns out. If it were me, I'd check the FPR again before I did the pumps. Pumps usually up and die. There's a flow chart at http://www.autozone.com/servlet/UiBr...3d800f917c.jsp for testing the fuel pumps, regulators and such. That way, instead of just replacing the pump to see if it fixes the problem, you can check the system thoroughly and (hopefully) know what to replace to fix the system before you cough up the money.

 

I need a new engine, but the current one will do for now until I turn my truck into an off-road only vehicle...

 

Mrshorty, everybody, thanks for the help, I love this site and i wish there were more just like it. I replaced the fuel pump and problem solved....runs fast now too. Sometimes I guess you gotta quit second guessing and trust your tests.......