I don't think the gauge I used was out of calibration. When I tried to diagnose a similar issue before I found this forum, I was told to check the fuel pressure. I bought a gauge and back then it read 38 psi at idle. (still have the pictures of the readout). I was told then it was good so I left it alone. Fast forward to now and my gauge was broken by a friend so I had to use a parts store rental. Came back with the same 38 psi. Think I am going to grab a new FPR on the way home from work today.

 

Yea I agree and didn't go into detail, hindsight perhaps should have, is a test of sorts.

I replaced ACT and ECT but did so on my 94 one at a time, ECT had no effect on issue I was having however ACT did, changing it corrected the problem. My 95 while was having no problem with it I replaced those two, the coil while doing a full tune up age of sensors unknown suspected to be original.

Point was rather than spend time taking readings with a meter swap them out with new sensors see if code/condition disappears. Condition of those two sensors at this point due to age would be questionable and often overlooked, that and not talking about top dollar parts or parts hard to swap.

 

So I checked the ACT and ECT this morning. They are both perfectly in spec hot and cold. I also pulled off the line from the FPR and put a vacuum gauge on the line. The FPR is getting the full 20 inches of vacuum so I think the regulator is at fault here.

I did have something new happen this morning as well. The #6 fuel injector was stuck when I first started the truck. This is the first time it has happened. Truck was making what sounded like rocker tick, but very loud. Put a stethoscope on each injector and found out #6 wasn't doing anything. Pulled the connector while it was running and that made no difference. I then gave it a tap with a hammer while it was running and it started firing just fine. Guess my JY injectors need replacing. So as of now I am looking at a set of new injectors and a new FPR.

 

Thought same thing when initially read it however its technically only 3psi over spec, fault in gauge or slightly high.

Would think it should be able to trim fuel even if 3psi over spec, spec is 30 to 45psi engine running vac line on, 5 to 10psi increase over that running vac line disconnected.

Little higher than mine but not much and going by that and the stated fuel pressure readings it is not over spec.

Reason I didn't get into it up to this point, may have come back around to it though.

Could do quick test/check with hand vac, don't allow vac to FPR to drop running self test that way see if any change/effect.

 

At this point I would never discount a few PSI over spec. Plenty of times Subford and others have pointed out what the values should be for good reason. Since the MPGs are low and the PSI is a tad high, start with the obvious first.

 

I am gonna grab a new FPR on the way home and a can of B12. Gonna run the can through and hope that's keeps the injectors happy until I can afford a new set of injectors.

 

Evan, you just rebuilt a set of injectors last year. Would it be worth it to pull the offending one to see if it can be fixed/rebuilt again? Maybe replaced with another rebuilt one? It's got to be cheaper than new ones and from your piece on rebuilding your injectors I can't see new ones being any better than your rebuilt ones.

Just a thought.

 

I was actually contemplating that today at work. I think I am going to pull all of them and bench test them to see which ones might be having issues. And yes, the price for new ones is pretty high, about $300...

 

No, not *all* sensors, just (and specifically) the temp sensors and only in certain cases. The thing about a CTS is that as it ages, it can get "dead spots" in its temperature range where it reads incorrectly at different temperatures while still reading okay at cold and maybe at operating temp. Or it can In order to properly test the CTS, you need a good, accurate thermometer, a stove, a chart of what the sensor should read at various temperature points and most of an hour of time. All of this for a sensor that costs... GASP... the princely sum of $9. The air charge sensor is the same thing, only you need an oven. And it costs, again, $9. How much is your time worth?

Temp sensors are one of those things that should be replaced at regular intervals (here's the certain case). If you have a problem that you suspect could be related to a temp sensor and you don't know that the sensor has been replaced in the last decade, it's a good idea to just go ahead and replace it based on time in service. If it HAS been replaced in the last decade, yes, go ahead and test it and find out what's going on. Just like when you get a new-to-you car, you change all the belts, hoses and filters if you don't know that they've been done recently.

 

I got to this thread late, but as RLA2005 mentioned, those fuel psi #'s don't jive. Either gauge is not calibrated correctly, FPR is failing, or problem with fuel pump. I'd suspect gauge or FPR and re-check.

 

I grabbed a new FPR today. I am going to install it tomorrow and then go to the auto parts store and check the pressure with the new one in.

 

Fair enough - I get your point.

 

Mine did too, truck ended up down the road at Ford for a look see. I wanted to talk to the old guy working there at the time.

He looked at it two for two days, took it for rides wouldn't do to him what it'd do to me you know how that works. He left is breakout box on it told me to drive it around let me know what the fuel trim did when it screwed up, another little box sitting on the dash connected to the BOB.

What it'd do is after a stop say a red light it wouldn't what I'd call a flat spot and not a hesitation but more combination of the two. Give it gas wouldn't go just ball less but only every so often.

Finally did it and got to point it'd do it everytime, ran down got him he jumped in so he could see/feel it too. The mixture would peg .9 volts full rich and for that brief moment WOT would bring it right out if it.

He said replace the O2 sensor I reminded him I had and due to the 173 code, didn't believe it was a problem to start as it wasn't very old but had already in attempt to correct the problem put another new one on it.

He said change it so I did, didn't help same problem. He said he didn't know what it was then we agreed he couldn't spend more time on it wasn't charging me for what he already did. He took the box off I handed him 50 bucks and left.

All sensors tested good I had swapped out MAP, Coil those type sensors from my other truck as it suffered no such issue. Put a new TPS on it in attempt find the problem.

Thought about it only part I had not tried was the ECT and ACT sensors. Rather than swap with the other truck I bought new sensors, swapped ECT no change, changed the ACT sensor and right out of the driveway I could already tell it ran stronger drove it around it no longer suffered the problem, no longer suffered 173? well might have been 179 for example possible I don't recall the exact code anymore.

After that little episode I figure its better off if just replace them especially if age is unknown.

Ran good after that couple three years later 172 system lean reared its ugly head...but I digress!

Anyway yea wouldn't hurt to replace the FPR that said I've yet to have one fail and would tend to think one fail low rather than high.

So passed the static pressure test time or two but sounds like it's going to be injector related and yea possibly a combination of the two. FP tad high / injectors dribbling fuel rather than spraying it.

Be interesting to hear results of testing after new regulator is in place, if that extra little bit of pressure is enough to cause a problem.

 

Well there was certainly something wrong with the FPR. I put the new one on this morning and then drove to the parts store to check the pressure. I made sure to get the same gauge that I used the first time as well. At idle the psi is right at 30 psi. With the vacuum line removed that goes up to 39 psi. On top of that the truck seems less sluggish and the strong smell of fuel is gone from the exhaust. I am going to fill it up today after I get my smaller tires put on and then the mileage test begins. (If your wondering, I am trading a co-worker my 33x12.5 Duratracs for his 31x10.5 Duratracs and some cash.)

 

Glad to see you got the results I would have expected for fuel PSI.

Be sure to recalibrate your PSOM for the smaller tires.