Diagnosis help, please

[npentyl]

hello, i have a 94 mazda b2300 2.3L 2WD ManualTrans and ve been having some problems. the truck runs quite smoothly after my tune-up, but now has a problem. when i drive and i take off in 1st gear the engine will suddenly die at end of block, use up the rest of the fuel in line and sputter out. i have to start it again and it dies pretty quickly. i get no CEL. i can park it and rev it all day, and it sounds perfect, but when i have load on it it cuts out. this typically happens in 1st gear, but has now spread to my other gears as well, rendering my truck undrivable. also it frequently has problems starting, it will turn over but not start... will start after awhile. also it will occasionaly start very rough and chug and sputter, usually fixed by turning it off and starting it again. and ive noticed the truck backfiring when slamming on gas. before this became a huge problem it would happen very rarely (over course of 4 weeks now), and has gotten progessively worse, now i cant get it down the block. also my last few tanks of gas have gotten really bad mileage, but i suspect it will be improved with the new MAF partially.

in my tuneup i have done the following:
replace fuel pump/fuel filter
replaced a bad MAF
cleaned my idle control
[by shop]had a water pump changed (was faulty) and the thermostat and hoses
changed plugs and wires
replaced air and oil filters
seafoamed crankcase (idle and rev for 10 mins before changing oil) and sucked up through vac line (twice, very little smoke)
changed serp belt
replaced battery and alternator (were both under warranty)

took it to a mechanic, who i am now in dispute with over the matter of lack of diagnosis, and during their brief inspection they checked my fuel pressure off of the rail and it tested within specs. he also sprayed along the vac lines and the engine did not rev. they suggested the MAF and upon replacing it the truck does run smother, but the dying problem still persists and they refuse to complete the diagnosis and want to charge me again for continuing the inspection, so in short i cant go back to these guys and have them check out the rest. cash is tight so i cannot afford to take it elsewhere to complete teh diagnosis, and i do not own any specialized instruments, such as pressure gauges and such, but do own a multimeter and a chiltons guide.

any advice on what to check will be helpful. its very frustrating since the engine is running and sounding like it did when it was new, i just cant drive it anywhere!

thanks for your time! ill update as i learn more about it.

tomorrow i plan to switch out the fuel pump with the old one temporarily and see if the prob is there and to again inspect the connections and such associated with pump, and to trace the fuel lines, looking for any big obvious leaks, after was advised to listen at the injectors for hissing, and possibly check throttle position sensor with multimeter and chiltons,

 

[41Ranger]

You said you just tuned it up. Do you have a reusable type air filter installed?

If you use a K&N air filter or other type of reusable filter, you can get filter oil on the MAF if you over oil the element. If this is the case make sure to clean it with a non residue leaving cleaner such as brake clean.

 

[schlutzer]

So it sounds like a fuel problem to me.... since you sound like you kinda like to do your own wrenching...go spend the 20 bucks for a fuel pressure tester and test it yourself...

I had an issue similar and it was the ground to my inertia switch....so i could rev all day....but the bumps from driving would mess with the bad ground and kill my fuel pump... I'n my case i just rigged up a Fual pressure gage from an old drag car my unlce had wrecked.

and while i don't think the MAF is actually causing the sputter and die and hard starts you are having clean it and see what happens ( do a search its been covered many many times)

 

[locovaca]

You said there are no codes, but I would run it through a KOEO and KOER test:

http://www.therangerstation.com/tech_library/OBD_I.html

Also, make sure your wires are on tightly and in the correct order.

 

[npentyl]

took off the bed and checked the fuel pump again. the wiring harness seems to have been eaten away a bit... i cleaned it and reattached and saw a slow leak on the hose... will replace hose and make a trip to scrapyard for a replacement harness and see if that clears anything up

 

[npentyl]

replacing the wiring harness and putting the old fuel pump seems to have fixed it! perhaps it was the connection that was the issue. also replaced the end of the fuel line connecting to the pump as it was dripping a bit. used one of those double ended hose connectors. heres a pic of the dissolving/breaking harness, and the dripping line was the one pointing to the left
<a href="http://s875.photobucket.com/albums/ab320/npentyl/?action=view&current=IMG_7732.jpg" target="_blank"><img src="http://i875.photobucket.com/albums/ab320/npentyl/IMG_7732.jpg" border="0" alt="Photobucket"></a>

<a href="http://s875.photobucket.com/albums/ab320/npentyl/?action=view&current=IMG_7740.jpg" target="_blank"><img src="http://i875.photobucket.com/albums/ab320/npentyl/IMG_7740.jpg" border="0" alt="Photobucket"></a>

 

[Loanranger]

use the IMG code, copy and paste

 

[npentyl]

oops! thanks for the correction!