11 miles a gallon and exhaust smells like gas

[maroon ranger]

I have a 94 ford ranger with a 4.0L that is getting terrible fuel milage. I completely tore down and rebuilt the motor this winter. Every seal and gasket has been replaced, new heads were put on and a huge list of brand new sensors and gadgets. (Fuel pump, fuel pressure regulator, maf, plugs, wires, coolant temp sender, iac, pcv, o2 sensors and a few others I can't name off the top of my head.

Anyways I have checked fuel pressure, compression and spark and they all check out! Everything is what it should be. I even traced down vacuum lines and replaced the ones that were leaking or looked like a problem.

And after all that I get a rough start up and when it starts it smells like gas, I have pinging under acceleration and terrible fuel mileage. Averaging 11-12 miles a gallon in town and highway driving under average conditions.

 

[SenorNoob]

Just thinking out loud but, stuck open injector(s) or bad (even though it's new) O2 sensor?

Any codes?

 

[RonD]

There is a "coolant temp sender"(1 wire) and an ECT sensor(2 wires)

The ECT sensor tells the computer the engine temp via coolant temp so similar to the "sender" for the gauge.
The ECT is the "choke" for a fuel injected engine, easy to test with OHM meter
http://oldfuelinjection.com/?p=28

If ECT is telling computer engine is cold all the time then it would be the same as running with the "choke" on in a carbureted engine

With key off remove a fuel injector connector and test wires for a ground, no injector wire should have a ground with engine off, test as many as you can get too.
A shorted to ground injector wire would mean when key is on injector would be open, 24/7.

If you have a test light just connect it to battery +, then touch the light to each wire for the injector, if it lights you have a short, and on the '94 I think 3 injectors would be open, batch fire.

 

[maroon ranger]

Thank you! I never thought about checking the injectors for some odd reason. Hahahahaha! But yeah ill give that a try tomorrow and let you guys know what happens.

 

[maroon ranger]

Had a couple free hours today and did some testing guys. The ECT tests fine so we can cross that off the list. But i was only able to pull 2 of the 6 connectors for the fuel injectors and both were on the passenger side. Anyways i took a test light and hooked it to the positive on the battery and touched each prong on the connecters and the light lit up on each one. Which as said before indicates a short, right? anyways i checked over all the exposed wiring before it goes into the factory wire harness and didnt find nick, scrape. rub or abnormality. So i wrapped the 4 wires i can get too with electrical tape for now. Looks like i will be pulling the intake manifold later tonight to inspect the rest of the connecters. Unless somebody says otherwise.

 

[RonD]

The way most fuel injection systems work is that when the key is on each injector gets 12v power from EEC relay.

The EEC(computer/PCM) then Grounds each injector when it wants it to open/fire.

Old systems used a Batch fire method, similar to a carb in that the point was to keep the intake manifold full of fuel/air mix no matter what cylinder was pulling in the fuel.
On a V6 that means 3 injectors would be open at one time.
So there would only be two Ground wires running back to the PCM, one wire for each set of 3 injectors, usual sets are 1-2-3 and 4-5-6, so left bank, right bank.

When Cam sensors were added there was a switch to the Sequential method, so each injector had it's own Ground wire running back to the PCM, so 6 Ground wires.

If you look at the wires you should see each injector has a Red wire, that's the 12v power, then look at the color of the other wire, if 3 injectors have the same color "other wire" then it's the Batch method, if each has a different colored "other wire" then its sequential method.
Batch fire Ground wire colors were often Tan and White

I am not sure if the PCM holds open the injector Grounds or if they are normally open.
So I would do the test with key ON as well, see if the Ground goes away with Key ON

 

[maroon ranger]

I just learned some new info! Thank you RonD! And yeah ill test that out tomorrow afternoon and check the color of wires and stuff. Ill report my findings soon afterwards. All in all I would just like to figure out why I am having these troubles so I can fix them and save up enough throw in my solid axle. Hahahahaha but the dude up above has other plans.

 

[maroon ranger]

So anyways....my past response was me being aniebreated or how ever you spell it. Hahaha but anywho I tested the two connections tonight and both were tan and red wires. With the key off and the test light hooked to the positive.......both sides of each connection lit up. Now with the key on.......none of the connections lit up. I even double checked my connection with the test light. Test light was fine. Anyways where should I progress from here? Be the strict diy that I am or take it to the shop and have them resolve it?