Yet another 7.3 cold start issue

[pt_Ranger_v8]

94 7.3 NA. Swapped into a 95 CC Body with a ZF-5 behind it. 256XXX Miles on the engine, though it was regasketed (no rings or bearings though) about 60K ago.

For reference, in the last month I have replaced glow plugs (Beru/Motocraft ZD-9), return line kit (Thanks Mel!), steering box (Redhead - it's nice), and 2 new GP65 Everstart Maxx batteries(Walmart )

It finally got cold here in Central Oklahoma - it's been down to the single digits for several days, with some pretty kickin' winds - 20-30mph at times. Kinda chilly.

This is the first time I've had this truck in 'cold' weather, so I wasn't sure what to expect. I did the batteries, gp's, and return line more for routine maintenance - after 2 years, it was time. The batteries were mismatched, and have been severely abused over the last year while I was deployed.

Anyway, to the situation at hand; Went to start my truck yesterday after being at work all day. The truck had been sitting in the parking lot for about 12 hours in 5 degree weather - I expected a hard start. I cycled the glow plugs 2 times, knowing it would need it. It cranked hard, then fired up. 10 seconds later, it quit - just straight died. Cranked it hard, no start. Got a jump, still no start. Finally broke down and used a shot of ether - fearing for my glow plugs all the while. It immediately fired, and proceeded to run like a champ.

Today, after sitting all night and day, I went to start it again. Same problem, except it wouldn't fire the first time. 1 shot of ether (while being jumped after running the batteries down) and it fired right up.

Right after I swapped glow plugs and the return line, I had an issue with a return line hat not being seated - fixed that and haven't noticed anything wrong since then (~3 weeks).

So, where should I start troubleshooting this cold start problem?

I intend to do a compression test on all 8 cylinders tomorrow. I expect the numbers to be low with this mileage, but I don't know how low.

I also am going to ohm out my gp's. From what I can tell though, the controller is working. When I cycle the key, voltmeter drops. Once I start it, the volt meter stays low (5-15 seconds, depending on engine temp), then returns to indicate charging. (incidentally, it's charging at 14.58 volts).

I am also wondering if the check valve that is supposed to be in the filter head is really there. Where would I find this thing?


Sorry for the essay, thanks for the help.

 

[fhafer]

Have you changed the rubber "olives" on the hard lines? They get hard with age and will allow air to enter the fuel circuit. The one behind the passenger side head was the culprit of my hard starts. Just a thought.

 

[chris142]

You need to fully charge your batteries. Thats going to take a very long time depending on your charger. Even down to 0 it should start up. If it dont theres no reason to crank on it till the batteries die. I wonder if your fuel jelled

 

[icanfixall]

Olives are a good place to start fixing things. You should have a nice tight fuel system. The check valve on the fuel filter head is by the schrader valve. Thats the end of the return line off the filter head. Hopefully you have one of those lines off the filter head. The valves do fail. They will fail and allow air to be sucked back into the filter causing the run and die. Then long cranking to refill the filter with fuel

 

[pt_Ranger_v8]

When I swapped in the engine, I had to run all new fuel lines - so I have hard lines to the mechanical pump on the block (with a piece of rubber line there), hard line to the filter head, which is running a wix 33417 filter - a one-piece filter setup. For the return, I have a hard line terminating at the drivers side head on the firewall, and a piece of rubber going to a 'T' in the return line setup. There's no rubber olives in the setup anywhere, that I'm aware of.

For the return line check valve, is it located inside the filter head, under the Schrader valve? Any way to test it? Where would I get a replacement? I've been on this board for 3 years, and this is the first I've heard of it LMAO

I'm going to do a compression check, and ohm out my glow plugs today. I'll also post a picture of my filter head setup later when I get done with the compression test and glow plug test.

Thanks for giving me some more ideas.

Chris142 - It's a 30 minute drive home from work. Solid mix of highway and city driving - no idling. I would expect the batteries to fully charge in that amount of time. I don't know the charge rates, but for some reason, I keep thinking that dead batteries should be charged well in 30 minutes - especially brand new ones.

 

[icanfixall]

These check valves are between the filter schrader valve and the vacuum pressure sender. They come in 2 different sizes. They can be found at Oregon fuel injection. Thats where I got mine. Be sure what size you have a need for. they come in 2 different sizes. One is 3/16 and the other is 1/4 inch size. The 7.3 engines can be either size too.

 

[pt_Ranger_v8]

Well, after a long day, it's running again. I don't know if the 60* temps were a factor, but it fired up after a few things.

Tested the glow plugs and the harness through the 'Z' bar. Each plug was under 1 ohm. (.3-.8). Then tested the harness and from each bullet connector through the Z bar back to the solenoid and it was .2 ohms.

Then I went to pull the battery cable off the solenoid, and found out the solenoid was baked. EEK!

When I loosened the nut, I twisted the stud right out of the solenoid Mad. Since I was already that far into it, I did a compression test anyway - highest was 490 psi, lowest was 350. Except for the low cylinder (#7), The others were great - 450-490 psi after 7 cranks of the starter. Sweet I double tested the low cylinder, and it was still low. Not sure what's going on there, but I'm not too concerned about it - truck seems to run just fine.

Anyway, replaced the GPS after putting everything together, waited for the WTS light (3-5 seconds) and it fired on the 3rd crank. I'm going to try it again in the morning when it's supposed to be 30* (without plugging it in), but I think the solenoid was engaging, but not passing enough current to make the gp's work correctly.



I did find the check valve - and it appears to be in fine shape. My question is, should I be able to hit the Schrader valve and get something (air or fuel) out after the truck sits for several hours/overnight? I would think if the system is functioning correctly, I should at least get a dribble of fuel from there. Thoughts?

 

[chris142]

Chris142 - It's a 30 minute drive home from work. Solid mix of highway and city driving - no idling. I would expect the batteries to fully charge in that amount of time. I don't know the charge rates, but for some reason, I keep thinking that dead batteries should be charged well in 30 minutes - especially brand new ones.

No way!!! 30 minutes wont even be a good surface charge! Id say 6+ hrs of constant driving minimum.

Many People just dont know how long it takes to fully charge a run down battery. You can get close by dividing the reserve capacity by amps. A 100 rc battery will take 10 hrs @10 amps.

 

[pt_Ranger_v8]

What's the ampacity of our alternators? Even the small ones are ~95 amps.

The reserve capacity is 140 or 150, per walmarts website...
http://answers.walmart.com/answers/1336/product/16782705/questions.htm?sort=recenta
And even at 80 amps should only take 2 hours to charge. (roughly)

Or is my math all wrong?

 

[chris142]

Your alternator may be able to put out 80+amps but they rarely do plus they back off the amps since a car battery cant accept 80+amps for vey long w\o exploding! Figure about 40a output for most of your drive divided by 2 batteries. Even @20A each battery will take 7.5 hrs to fully charge!

 

[chris142]

You really need to get a good battery charger and let em charge all night then let your alternator maintain the charge instead of trying to fully recharge run down batteries.

 

[pt_Ranger_v8]

Good points. Thanks for the insights!

 

[icanfixall]

The alternators on cars and trucks are not designed to recharge a dead battery. What they are good at is refilling the battery after we start the engines. Once thats done their only purpose is to supply amps and voltage to every piece of electrical equipment being used on the car or truck. Besides a big stereo the largest drain on an alternator is the ac clutch.

 

[pt_Ranger_v8]

All the recharge talk aside, I went out this morning, and the truck fired right up after 1 cycle of the glow plugs.

For reference it was ~20*F, with a 20mph wind straight into the grill over night (~12 hours). Wind chill was about 3*F.

I'm going to go out on a limb and say that replacing the glow plug solenoid fixed my hard starting issue. (fingers crossed when Isay that!)

 

[pt_Ranger_v8]

Yesterday, it was another cold, windy day. When I left for work, I plugged the truck in for my wife. About 3 hours later, she tried to start it, and it stalled shortly after starting. A classic air intrusion symptom.
She started it a second time, same result. Then lots of hard cranking, blah blah blah.

I don't see *any* fuel leaks on my return hats. Where else should I be looking for air intrusion? Being that it only runs for 3-5 seconds (after sitting 1-2 days), how close to the filter head should I be?