Look for the next step/s in the diagnosis process.

[Bgunner]

Lets start with the vehicle first shall we:
94, Ranger super cab, 3.0L, manual transmission, Stock suspension and drive train, Code 84: 7.5″ rear axle open with 3.45 gears, 146,xxx miles. No CEL

Issues: Shaking while under heavy load, climbing hills, in first gear with RPM's between 1000 -1600. This does not happen in higher gears/speeds. (EDIT the shaking is not violent but I can feel it mostly through the shifter but also through the floor.

When first started for that day the engine will shake and run rough and smooth out usually within about 5 seconds but has gone on for longer. By running rough I mean it acts like it has a skip but it goes away.

When warm the Engine takes 4 or more cranks to fire and some times runs rough for a couple seconds and smooths out. By cranks I am referring having compression strokes on a single cylinder

My first question is would this be normal for this thing with the gear ratio and engine? I have never owned a 3.0L ford engine before so I don't know what is normal for this thing and what isn't.

Continuing on, I purchased this truck just over a year ago and this truck has done this since I got it. It did have a skip when I got it so I replaced the following: Accell Super Coil, E3 plugs, Taylor cap, rotor and wires, the distributor bushing was worn to so I changed the distributor as well.

Just before I got the truck the fuel pump and filter was replaced so that would make it around 2 years ago. The truck has been driven about 10,000 miles since. I have cranked the engine without spark and got 3 wet plugs and 3 not so wet but all 3 of the not so wet were about the same. Cylinders 1-2-5 had less gas on them than 3-4-6, if it helps. This test seemed to be inconclusive for bad injectors. I also cranked the engine with the fuel shut off, flooded mode, and none of the cylinders fired so I believe don't have a leaky injector. While doing these tests I also changed the plugs again with the E3's. I have also run 4 or more bottles of injector cleaner through it along with SeaFoam, once through the fuel and twice through the intake.

That takes care of spark and fuel now on to air, I installed a Fram Air Hogs air filter, I have cleaned the MAF sensor twice and repaired holes in the plastic tube intake, cleaned the intake with spray intake cleaner, along with 2 cans of SeaFoam this includes the throttle plate and IAC that could be gotten with it still attached. Pulling the plug to IAC drops the idle but runs smoothly, well as smooth as it does with it plugged in, at about 500-ish RPM. PCV valve was good when I first got it but now I say it I should check it again. I have changed the engine temp sensor hoping that would help the hard start when warm condition but alas here I am.

What tests should I perform next, if this isn't just in my head that is?

 

[Denisefwd93]

You need to check actual fuel pressure, not assume its ok because the pump was replaced.

It could be a very very small head gasket leak or an intake leak but I'm just guessing on that.

One of my pet topics is catalytic converters.

My car had a impossible to find "shake" for years. One day the ignition coil was completely dead, we replaced it and the engine ever ran better than ever!

 

[Bgunner]

@Denisefwd93 - I'll need to buy fuel pressure gauge as my friends wont work on my truck because the shrader valve is to small. I'm not into buying cheap tools so that can't happen till at least next month, Kids birthday this month. I do have a compression tester but I fear the plugs... that right rear one, you know, the one with the evap box right in the way. I break that one every time, I'll need to get a swivel headed ratchet, yup that should cure that. I'll post back with compression readings on all cylinders probably wont be till the weekend though.

On the subject of fuel, the FPR does not seam to be leaking into the vacuum system, I looked for kicks and giggles. If it were a fuel delivery issue wouldn't have other effects as well? Like loss of power, stumbling at higher speeds including climbing hills? It pulls steadily and smoothly up over the mall road, which is a good hill climb, (edit) about 2 miles or so, since I live in the mountians.

The shaking only happens in first gear, and between 1000 - 1600 or so RPM's. This is most prevalent when I turn onto my street. It's a hill, for sure, with a rough transfer between the two surfaces. Many cars scrape there nose on the road so speed coming up it is not an option.

With as little power this Vulcan 3.0l actually produced, peak HP is around the 3500 RPM mark and torque I believe peak is around 3000 or so, how likely is it that the engine is stumbling due to lack of RPM?

 

[Denisefwd93]

I wonder if there's any Ranger on the road that doesn't shake somehow or some way. I just throw things in here there to get people thinking it's not that I'm an expert on engine troubleshooting. I try to stay in the confines of HVAC and Wooden Boat restoration. I don't mention the other stuff because it wouldn't interest the guys lol. But we can leave it at fine dining Opera and theater lol

 

[Ranger850]

Lack of rpm for sure. I have a 3.0 and as long as you stay in the gas and dump the clutch. Hold to 3,000 and switch gears.

 

[Bgunner]

Update: Results of fuel pressure test: KOEO results are 36.5 psi once the gauge leveled out and held pressure for about 5-7 mins then dropped to 32.5 psi 11 mins later, once the key was turned off.

How long should the system hold pressure? and How long should it take for the fuel pressure gauge take to level out? It took about 1.5-2 minutes to level off and stay steady, this is why I ask.

I have not gotten to the compression test due to hurting my back while greasing the front end so pulling on a ratchet is out of the question till I stop hurting. I will get with the results back once the compression test is done.



EDIT: While driving the other day I noticed that the shaking occurs between 1000 and 2000 rpm so this is not just a low RPM/lack of power shaking issue.