86 BroncoII 2.9 4wd auto trans- just got back from reman engine install. It will lose power when running at any rpm I notice black smoke coming out when this happens. I try to get codes and KOEO shows up a code 67 KOER shows nothing not even engine ID. The morons who did engine job can't figure it out i've given up on them. The engine runs smoothly and has power until it stutters. I attacked it as a fuel problem first and thats where I am now. Oh yeah O2 sensor was replaced no burnt wires. I changed fuel filter 1st no major crap in filter, clean fuel. Hooked up pressure gauge, had to turn on key 3-4 times to get pressure up it read 40 lbs. When running it reads 30 lbs at idle at 2500 rpm drops to 28 lbs. starts to sputter and pressure fluctuates up and down a few lbs, no lower than 28 lbs. I went for the easiest first and replaced fuel regulator this improved pressure pickup when you turn key to on. Between fuel filter and regulator change sputtering improved but is still there. I unplugged high pressure filter and pulled incoming fuel line. I ran the low pressure pump for a couple secs and got clean gas to pump out into a jar.I hooked everything back up and did the same W/ hi pressure pump and got clean fuel at rail. I saw no kinks or leakage in fuel lines. I guess what I'm asking is is this pressure acceptable? I dont want to install a new pump or pumps for nothing. I replaced fuel pump relay and hi pressure pump plug last year they're good. Sorry this is so long winded I tried to give all details I could. I triple checked engine timing also. Also when engine sputters give it a little gas and it picks up -this improved w/ filter change also

 

I checked the specs posted under fuel pressure testing in Ken00's technical information post. According to his information, an '86 should never fall below 35 psig. If your gauge is accurate, then it looks like your fuel pressure is low. The black smoke suggests that it's running real rich when it stumbles. I know you replaced the FPR, but could the new one have a bad diaphragm? Check for gas in the vacuum line to the FPR. I also wonder if you might have an injector (or injectors) that, from crud or an electrical fault, is occasionally sticking open, flooding one or more cylinders. Does the fuel rail hold pressure for any length of time after the pumps are shut off?
(BTW, Ken, Would you double check the table at the bottom of the aforementioned article? This must be the first time I looked at it closely, but it looks like you have the columns labeled KOEO and KOER backwards.)

 

how do u change the fuel filter? is it very hard? my friend said he'd do it for a few dollars, said it was pretty simple, i just want to know if i can do this myself

 

Fuel pressure holds well after shutdown- Romer' what year Bronco do you have?

 

What year is your truck?

Will check it out, THANKS.

 

mine is an 86

 

i have a 90 4x4 2.9L how much do these usually cost also? thanks again

 

nijwnfi, I think 28 PSI is to low, can you find a way to test the pressure at the HP pump. How much gas did you get when you ran the LP pump for a few seconds?

RomerB2, ON a 90 the filter is on the frame rail behind a shield, just disconnect the power at the inertia switch, crank it to relieve pressure, remove the shield and if I remember correctly the filter connection are a spring lock type. Be careful, you will still get some gas coming out.

 

Ken, I'll look into pressure check on hp pump as soon as I can. Also lp pump put about 2-3" of fuel, steady stream in a measuring cup. I talked to a mechanic at a Ford dealer he said when I unplug regulator, pressure should go well above 40 psi when engine is running. The gist I got is pressure should not decrease with rpm increase but stay steady. Also could map sensor going bad contribute to problem of stutter/rough running?

 

I forgot to find the specification for the LP pump, will get it tomorrow but that sounds OK. Will also check on the pressure with the FPR vacuum disconnected. A bad MAP can cause many types of problems but it should give you a code.

 

Got home early today so I said the heck with it and got a hp fuel pump. Engine starts quicker but pressure is only up a pound or 2 at idle still about 28 at high rpm. Also on driver side of engine block midway down is a sensor that was unplugged it is a 2 prong round plug- oil pressure? black plastic plug. Engine runs great until it warms up completely, then intermittent stumble. Its gotten better it used to stall out completely so I guess i made some headway. I still get no KOER codes even using test light and jumper. I never have even with old engine. Old engine did not have this problem. It spun a crank bearing. ALso I hooked a vacuum gauge up to manifold reads about 18 lbs at idle- pressure does not drop when I rev engine and hold it but it spikes up to 25- 28 lbs for a sec when I let off. Is this normal?

 

That's either a bad vacuum gauge or you're not reading it right. At sea level, a perfect vacuum is only 14.7 psi (29.92 in Hg). Did your gauge mean 18 in Hg vacuum? That would be about normal.

 

sorry it is 18hg- got units of measure confused

 

Finally found the LP pump sepcification, you should get 6 oz / 5 seconds, sounds like you got that.

When you say "no codes for KOER" do you mean only pass codes or none at all?

 

I get no flashes at all not even engine ID I hear a loud click when I connect jumper and rpm fluctuates for a sec thats it. Ive left it hooked up for a couple minutes - no flashes