CAT 3126 No Start

[gfs1943]

Due to circumstances beyond my control, I have not started my coach with Cat 3126 for about six months. Went to get it ready for the summer today, but the engine won't start. Batteries are good, starter turns it easily, but no firing at all.

Tank is full of fuel. I tried the manual primer pump, and it feels like the fuel system is fully primed. I drained the fuel/water separator (no water visible, only good-looking fuel). After that, I got about a stroke and a half on the manual primer pump. Really feels like there's plenty of fuel in the system to that point, but it's not getting to the injectors. Any suggestions? Thanks for the help.

BTW, the generator started quickly and ran flawlessly.

[mchero]

We all learn!

[gfs1943]

Not a battery issue. However, I think you're on the right track with the ECU. After trying to start for two days, the only thing I did differently was leave the battery disconnect ON overnight, instead of disconnecting like I usually do while in storage. Next day, the engine started like it had just been shut down a few minutes ago.

Once again, I thank everyone for their suggestions. I always learn from these forums.

[randallb]

In hind sight I am willing to bet a battery issue. Occasionally with an electronically controlled engine the battery voltage will drop below the voltage threshold required to fire up the ECU. After the battery sat for a while the surface charge became enough to fire the ECU. Make sure your battery is good and fully charged.
Randy

[gfs1943]

UPDATE:

Yesterday I called Good Sam. They tried to get me a mobile mechanic from Holt Cat in Waco, but none available either this week or next. Holt did tell me (relayed thru Good Sam) that if the coach was towed to their facility, they would be able to look at it within two days. I really didn't want to have it towed, even though GS said they would cover the tow cost.

GS located a mobile diesel repair company in Hillsboro, less than 15 miles away, and they agreed to come look at the coach within an hour. I went to the storage facility to take off the engine covers, etc. Before I did anything like that, I tried the engine start one more time. It started like it had only been shut down an hour! Just after I got it running, the mobile mech called to tell me his mechanic was leaving within 20 minutes. I told him about the coach starting and everything looking good, so we cancelled the service call. I hooked the CR-V behind the coach and drove it to my home, where I am doing all the maintenance things needed to travel.

Kudos to Good Sam -- they went "above and beyond" in my book. This was the first time I've ever called them. My GS road service contract expires at the end of July. I WILL renew.

[MikeSW214]

Yes cat calls it IAP....ICP, some of my International/Navistar was seeping in.

[dougmac]

To troubleshoot the problem you have, its best if you have the diagnostic software to view the IAP (Injector Actuation Pressure).

The most common not start I see on this engine is high pressure oil leaking by the injector o-rings. This causes low IAP.

To check the o-rings. I remove the valve cover and crank the engine. If I see oil leaking out between the injector body and cylinder head, the o-ring on that injector has failed. There is some oil in the area around the injector all of the time so, you would be looking for one that had an excessive amount of oil forming around it.

[MikeSW214]

Your 3126 like the 3116 are HEUI systems. You have a oil and fuel channel in the head. This system need 750 psi of oil psi for fire the injectors. If the injection control pressure sensor is not showing the psi the computer will not fire the injector. If there is no fuel the intensifier piston in the injector will sound like some one rapping on the block as the computer fires the injector and can possibly destroy the injector.

[gfs1943]

aztortuga wrote:
Is it possible that your primary fuel filter is plugged? The one mounted on the engine. I believe the filter with the water separator is a secondary filter although it is installed in the first position between the tank and then the engine. I would change out this primary filter and see how it goes.

The filter shouldn't be plugged, but that's one of those things you never know until you try. I have new filters here, so I'll try that tomorrow. Also, I know that my power supply wires are good, but I haven't started cleaning grounds yet. I'll also try that tomorrow.

The coach is parked in my (rented) covered storage area, on gravel, so it's a pain to get under. I do have a throw rug I can use to lie on while checking the grounds.

The fuel filter is accessible by taking off the rear cover under the bed, so I can change it from above. I just need to put a drain pan under that area so I don't stink up the storage lot with a bit of spilled diesel.

Whenever I get this problem resolved, I'll post the solution here. Thanks to all of you for your suggestions.

[Retiredblade]

Mike Hohnstein wrote:
click

Don't look like any lines to crack here.

There's not, haven't been around a Cat 3126 for many years, I dislike those engines very much. I remember now we had two Cat 615 paddle wheel scrapers with small Cat V8's in them and they lost their prime all the time, the mechanics hated them, but their injectors were on the side of the engine with a hand pump, they took a 3/4" wrench to loosen each injector to bleed them. Don't know why they always lost their prime, those were miserable engines also, talk about loud!

[aztortuga]

Is it possible that your primary fuel filter is plugged? The one mounted on the engine. I believe the filter with the water separator is a secondary filter although it is installed in the first position between the tank and then the engine. I would change out this primary filter and see how it goes.

[mchero]

Keep us posted on your progress. HOPEFULLY it will be a short & sweet fix!

[gfs1943]

bkd148 wrote:
Find the fuse for the ECM and check it. On my last moho with a 3126 the fuse was by the batteries and one of the blades corroded thus loosing contact. Replaced fuse and all was good again.
Marty

Thanks for all the suggestions. Yesterday I disconnected all wires at the chassis batteries and made sure everything was clean and shiny, including the 20-amp fuse Marty referred to. Still no joy.

There are no injector lines to crack open; the injectors are under the valve cover on top of the engine.

I haven't tried to pull any codes yet, but doubt that there are any since the engine was running fine last time it was parked. There is no smoke when cranking; it acts like there is no fuel at all getting to the injectors.

Next step is Good Sam service call. I don't want them to refer me to a RV mechanic; I need a Cat engine specialist. I may have to contact Holt Cat. I'm on a limited budget so I wanted to fix it myself, but I just can't do everything I used to. Anyone else have that condition?

[msmith1199]

mchero wrote:

msmith1199 wrote:

Tom/Barb wrote:

gfs1943 wrote:
Due to circumstances beyond my control, I have not started my coach with Cat 3126 for about six months. Went to get it ready for the summer today, but the engine won't start. Batteries are good, starter turns it easily, but no firing at all.

Have some one crank the engine as you crack each injector line at the injector, when you see fuel emitting from the injector line tighten it and move to the next, it will start firing 1 cylinder at a time, when you have enough cylinders firing it will run without the starter's help, continuing bleeding each injector.

Is that sort of looking for a natural gas leak with a match? I realize diesel fuel isn't as explosive as gas, but your method here seems a little risky to me. Not to mention can you even get to the injectors to easily do this while the engine is being cranked?

Read the post, we are talking diesel, not natural gas. Cracking the injector fittings to bleed air is done all the time. If you have a better way please let us know.

Read the post, I said that!

[bkd148]

Find the fuse for the ECM and check it. On my last moho with a 3126 the fuse was by the batteries and one of the blades corroded thus loosing contact. Replaced fuse and all was good again.
Marty