fuel system issues.

[toyrunner95]

I have had my 87 m1008 cucv for about a year now ( yes 87 checked the vin it was manufactured in Jan of 87) and I have been slowly replacing seals and sending units. The first was the tank fuel level sending unit. I pulled the bed and the tank pick up tubes and they r in good condition. I then had a leak in the diaphragm in the lift pump. So I changed that. Then my filters got clogged so I went to pull those and change them when I realized that the out tube from the factory filter was stripped... awesome. So since it was in a crappy location anyway I bypassed it and ran a new big filter with a primer housing so I don't have to crank and crank to get it primed again.

Anyway on to my problem. When I cold start the truck it has issues staying running and puked blue black exhaust. I know that means not fully combusted fuel. So there is air in the lines. When I replaced the fuel lines I put clear lines on so I can see where the air is commingle from., he only thing I can think of is a bad check valve in the lift pump.

Has any one else had issues with loosing prime overnight?

 

[m38inmaine]

Check to make sure the cold start solenoid is working. Sometimes the temp sensor for it goes bad and makes for hard cold starting.

 

[toyrunner95]

Check to make sure the cold start solenoid is working. Sometimes the temp sensor for it goes bad and makes for hard cold starting.

Where might that be?

 

[Screamin' Metal]

On the firewall just to the left of the brake booster. Contols your glowplugs. Check those too to be sure they're working. After you turn your key on, you should hear a thud after about 10 to 15 seconds....Those glowplugs ought to be nice and hot. Shows up really well on IH should you have a temp gun....

 

[Hasdrubal]

"On the firewall just to the left of the brake booster" would be the glow plug relay. The cold start solenoid is in the Injection pump, under the pump housing cover. There is a green wire to the rear most connector, it also connects to your fast idle. The pink wire is your shut off solenoid. The sensor is on the rear passenger side head, follow the wire. Does your truck engage high idle when cold, should sound rougher as the timing is advanced 6 degrees. If it is your temp sensor, be careful not to over tighten it, or it will snap in half. Long ago I wired an illuminated rocker switch to the circuit, bypassing the sensor, so my system is completely manual.

 

[toyrunner95]

I bypassed the glow plug b.s. awhile ago. I got tired of that stupid relay so I just put a 24v switch and solenoid on the glow plugs. I'll check the warm up sensor thingmabob tomorrow morning. Thanks for the advice!

 

[toyrunner95]

well i went to start the truck today.... it lost prime entirely. so i had to re prime it... again. BUT! on the up side since i put clear fuel lines on it, i can see where the air is comming from. i need to go through my lines and make sure everything is tight, replace the lift pump, and put new hose clamps on everything.

 

[Tulsafireman]

On the passenger side frame rail there is a piece of hose connecting the metal fuel lines. One of the first things I did to my CUCV was to mount an electric fuel pump on that frame rail and hook it in where the piece of hose connects the two metal fuel lines. Has power anytime the key is on. Eliminates a world of problems that plague the CUCV fuel systems. Just a thought...

 

[mudluscious]

Tulsafireman, can you elaborate on this little electric fuel pump? I'm a newbie to CUCV. Thanks.

 

[toyrunner95]

UPDATE. I finally had time to get under the hood of the beast and check things out. i took the air cleaner off and started looking for issues. the truck had lost prime again and i had a hunch as to where the leak/ leaks were.

on the new filter housing and filter there is a water seperator bowl on the bottom, i noticed that the o ring had not sealed correctly and was leaking a little bit of fuel. so i used a hammer and a punch to loosten it and put a new o ring in it. then i started to prime it and listen for hisses and things. the first thing i noticed was, there was a hiss comming from where i had connected the fuel line to the in line on the injector pump. the hose clamp was too big. so i replaced it and stopped the hiss. so i kept priming and i heard a hiss comming from the little tube that connects the injector pump to the little module on the front of the pump. there is about 3 inches of hose that still needs to be replaced. but i had other things to do so i skipped it and pressed on.

i hopped in the truck and cranked it over..... sorf of... then it died. CRAP!!! the batteries are dead. oook so i pulled them out, bought 2 fresh ones. group 35 or 36 something or others. plugged them in and then primed the pump a couple times and cranked it over. it almost started, did it again, got closer, then third times the charm it fired! got the truck all warmed up, drove it around all day, ran some errands then parked it.

now, 24 hours later, i got home from work and decided that i should check it. to my suprise, there was NO air in the fuel line. could it be that i had found the source of the problem!? no such luck. i still have a very rough start, the glow plugs are AC Delco and i put them in, in august. they arent that old. i tried the glow plug hold and warm them up a couple times and it still caughs blue untill all the cylinders are fireing.

so now that i have eleminated alot of the issues, i am back to my original problem. do you think its the little hose or the check valve in the lift pump. now keep in mind that all this started when i changed the lift pump.

 

[detroitmuscle1986]

My truck does the same thing. When left overnight the fuel drains back and causes starting issues the next morning. The cause of our drain-back is a bad throttle shaft seal on the IP. From what I have heard this is a fairly common place for the IP to leak, and maybe a place you'd want to check. Just throwing out ideas here. Good luck!

 

[Skinny]

I would recommend against trying to band aid problems with electric pumps and such. Regardless of your fuel delivery system, if the system is losing prime it is for a reason. Triple check all of your connections and seals, you also may have an issue with the IP losing the prime and not the lines. Either way, get it resolved and then worry about the electric pump upgrade.

I used single crimp stainless bands instead of hose clamps for this reason, I don't want to go back through every few months and recheck hose clamps.

 

[toyrunner95]

i dont plan on putting an eletric pump in unless its strictly a backup. the factory system workes just fine as long as theres no air in the system. this weekend i am going to change that little hose and pickup a check valve. ill start with the little hose on the injection pump.

 

[toyrunner95]

I changed the lift pump again suspecting that there might be a bad check valve on it. No luck. I put a secondary check valve between the lift pump and the filter. No luck. So now it comes down to the rubber return lines. They are old and need to be replaced anyway. Then I will check the tank connection lines. They are pretty old too. From there I might be forced to check the IP.

I've tightened all the hose clamps that I can find. Could it possible be a bad injector not firing completely?

 

[toyrunner95]

So after much conversing with coworkers we narrowed the problem down to air in the lines.... we think.

I came home today determined to figure out what was going on. I took the air cleaner off and started following the fuel lines from the lift pump to the injector pump. Tightening everything as I went. I started the truck with a few pumps of the primer and still it mis fired. So I cranked a bit then check the clear line for air. Cranked a bit and checked. I got it running and it was running worse than before. Then I noticed a white foam in the clear line coming from a loose clamp. I re-tightened it and got it to stop. I'm wondering if the line I put there is too small and restricting flow.but I doubt it. I'm about to start replacing all the lines with clear ones to see where the air ends up.

 

[Crash_AF]

Ok, you're chasing a problem that might be a problem, might not.

Have you checked the cold advance on the pump, and the temp sensor for the cold advance on the passenger cylinder head? If those aren't working, you're going to be making blue/black smoke and poor idle until it gets some heat built up.

This sounds like more of your issue because you said once it gets warm and you drive it, it behaves all day long. If it was drainback or air leaks, the problem is less likely to go away when warm.

Later,
Joe

 

[toyrunner95]

No I haven't checked those. I'll look into it.

 

[Shankem-Deep]

Well....what did you figure out? Threads not being finished doesn't help anyone.

 

[toyrunner95]

No I haven't but I'm still working on it. My head gaskets were leaking out the back so I'm in the middle of replacing them. So far I can tell that my #3 cylinder was the one misfiring on the drivers side. There was a lot of carbon build up around the exhaust valve. So since I'm doing head gaskets I'm changing the temp sensors and possibly narrowing down the injectors. I will update this. Give me a couple weeks. It may be that I wasn't getting full compression out of that cylinder causing it to mid fire till it warmed up. The gaskets looked pretty old.

 

[toyrunner95]

alright, yesterday i got may passenger side head removed, cleaned, and back on with a new head gasket. from the looks of the gasket, i was mere miles from it going legs up. 3 of the 4 cylinders were carbon scored and the gasket was looking bad. so i think it was a lack of compression. when it would heat up it would seal again. also just from me starting it and pulling it into the garage there was a trail of drips and leaks out the back. of the heads. so yeah im praying to all the gods i can think of that this was the problem but at least i fixed a leak.

also by chance, does anyone know what would cause a transmission leak while its parked? i have had the thing in the garage for a few weeks and there is a red puddle in the middle of the floor. along with a few gallons of coolant, a quart of oil, PS fluid, grease... the usual.