i haven't cranked my truck in a week or two, and last few times it has run pretty poorly. i figured that was due to the gas getting a little old. so i started it yesterday and the smell of fuel was STRONG. my buddy was standing beside the truck and noticed something leaking and running down the driveway. it was fuel. we searched high and low for the leak and it was running out of the exhaust. note that the exhaust stops about a foot after the O2 sensor. so basically it was running so rich that it was just dumping it out. there is the smell of gas in the oil as well.

i didn't try to do any troubleshooting yesterday since i didn't want to burn the truck down. but today i checked the codes and all i got was a 54...low voltage to the fuel pump...no big surprise today since i had to jump it off yesterday. but this couldn't have been causing the richness because there was 14+ with the engine running and the jumper cables were still hooked up.

i checked all the injectors and they all read 18 ohms. when i checked the voltage at the injectors with the key on, they all had 12 volts....between the 2 pins, with all of them disconnected. both side read this way. i know it's just supposed to have 12 volts on one pin and the other is a pulsed ground by the ecm. both of the wires have some resistance to ground with the key off. with the key on, the hot pin has 12 volts and the switched ground pin has about 20 ohms to ground.

i don't have a noid light, but i guess i need one right? has anybody got any suggestions on what i should check next?

 

don't run it like that anymore ...could wash out the rings and ...well you will have more problems then fuel issues.

 

yeah, thinning the oil out like that can't be good. especially since i only have about 5 miles on the motor since the rebuild.

 

You have one or more injectors stuck open. Change oil immediately and replace injectors before you start it again.

 

ok, i got some oil and a new filter. i also picked up a set of noid lights. is there any way to tell which ones are stuck open, or just the shotgun approach?

btw how many quarts of oil does a 305 take? the motor didn't have a dipstick or tube when i got it and i'm not sure if the chrome one i got at the swap meet is the right one.

 

u gotta get a pressure gauge for the leak detection, and 5.5 quarts, i usually put half in the filter and then throw 5 in the valve cover and end up perfect.. plus no dry start

 

does the pressure guage go where the schrader valve is on the rail? do i just hook it up and turn the key on to build pressure, then turn it off and see how quickly the pressure bleeds off? do i need a special type of guage? special fittings?

 

yep that little valve with the cap on it on the rail, usually u can rent a Fuel pressue tester kit and they have gm + ford etc adaptors

and yeah u got it down, see how long it takes to go down

 

Did you check the Fuel pressure regulator? If the rubber diaphram breaks, then a n unregulated amount of fuel will flow up into the Plenum, in the little tube that curls up from the FPR. If there is fuel in the Plenum, or fuel coming out of this tube, then the FPR is broken.

 

thanks, i'll check into that this afternoon. i've been wondering about the FPR since it's probably 20+ years old.

 

Can the diaphram be bad and not have fuel in the little tube? I am having similar issues, not as extreme, but fuel fouling plugs within minutes at idle. Holley AFPR (approx 2 years old), new cap,rotor,dizzy,wires,plugs. I had 24# svo injectors and a hypercrap chip, I put the stock chip and injectors back in to rule that out as possible cause.

 

ok, i FINALLY got around to checking the fpr and it was bad, fuel coming out the vaccum line. so i got a new stock replacement. i read so many horror stories about the adjustable ones and didn't want anymore problems.

so i put it in today and hooked up my brand spankin new hypertech fuel pressure guage to the schrader valve. the first time i turned on the key the pump ran for a second or two and the PSI went to 10 and then i turn it on again and it went to 20. the last time it ran for SEVERAL seconds and jumped up to 90 PSI! that was about 20 minutes ago and it very slowly leaked down to 65 psi and has been holding there for about 5 minutes.

at this time the plenum and throttle body are still off and i was wondering if there was anything i needed to check out before i reinstalled them. if it had just gone up to 40 something i would just throw it all back together, but jumping up to 90 has me concerned. is it somewhat normal for the pressure to spike or do i have more issues?

 

Do you gotted a stock fuel pump, or something special?
I would get some expert advice borefore proceeding.

When my FPR diafram broke, I had Massive black smoke, and fuel even coming
out of the front of the Throttle body, into the air intake ductiing

 

Have you replaced the fuel filter recently? If you havent I would replace it. If you have there is a chance you put it on facing the wrong way.

I would start looking fro obstructions in the fuel lines. The best thing to do is start cleaning out all of your fuel lines between the tank and your fuel pressure regulator. This can be a ccomplished by doing small sections at a time and disconnecting the feed lines and return side of the rails and lines. I even did the lines leading to the tank that woudl be by the rear axle where you can disconnect them and have someone either plug the end of the line for you while you spray carb cleaner in them and then use an air compressor to blow the lines out one at a time. This can help deposit build up as these cars are old.

 

You can rule out a stuck injector very easily. You need a mechanic's stethescope, or use Mr. Screw-driver. Get a long ones, and put it on the injector one by one, put the other end to your ear, you should hear clicking. The one that isnt clicking is stuck.

 

i thought i had my preferences set to email me about replies, but i didn't get any. that's why it took me so long to reply back. thanks for all your suggestions, i'll check them all out.

I'll certainly try flushing the lines, i've got a fuel cell i need to install so i guess that would be a good time to do that too.

i can't remember what kind of fuel pump i have. it's an external pump, but it's a parts store brand....i think partmaster. i can't remember what the part number was. it was similar to a walbro. the stock nissan pump only put out pressure somewhere in the upper 30's

i replaced the fuel filter with the stock replacement for my truck (since it fits the clamp) when i installed the fuel pump a few months ago and i haven't driven my truck much since then, but it ran GREAT with the new pump. the filter has got an arrow showing the flow direction so i know i got it right.

 

You can check the injector pulses by fitting a 12v LED across the two terminals of the harness, it should pulse under cranking.
You can also piggyback them to the injectors while the engine is running, looks very pretty, lol.

 

last time i had a stuck injector i primed the fuel rail showed 0 psi on the fuel pressure gauge, pulled the spark plugs till i found the one filled with gas.