Starting issue CAT 350 2006

[capnj]

Let me throw this out there and see there are any answers that might stop my problem. Cat has always started fine on first crank over last four years and roughly 25000 mi. Had my unit's oil and filters changed a few months ago, including gen set, at local freightliner dealer. After returning home it sat for about a month. Went to start it up for a 800 mi. round trip. On the initial crank it tried to start but then went back to just cranking. After about three more sessions of just cranking it started up. Let it run for about 1/2 hr. and turned it off, then restarted it . Started just fine, took trip and after 3days cranked it to come home. Same problem. Back home I took It back to freightliner. They said at first that maybe a fuel filter gasket was not installed properly ,thus causing loss of pressure, checked ,but no problem . There are no fault codes showing. Next they checked fuel lines etc. and fuel. Found fuel had some sludge in it , drained tank installed new filters. I brought it home and let it sit for a week, then tried to start it .Same problem, wants to start then goes back to just cranking. They said bring it back so they can check fuel pump ,but I can't quite see this since once it cranks it starts and runs fine over next couple of days. Any ideas ?

[twinboat]

They may be a slight air leak in the fuel line. While sitting, the air leaks in and the fuel drains back to the tank. It doesn't take much for this to happen and it usually doesn't leak fuel out.

It first starts on the fuel past the leak and then gets to the air in the line and stalls out. A few attempts at starting pushes the air thru the system.

It sounds like they are using trial and error, rather then troublshooting the problem.

Hopefully you'll get the right guy to figure it out.

[CountryB]

It's hard to troubleshoot a problem when you have one chance to test your theory, then the engine starts up and you have to wait a week to check the next possible thing.

If your fuel is draining back out of head (or draining back somewhere) and it takes a week to show up, it may be desirable to put a fuel pressure gauge on the engine (in your yard) then wait a week and see what the pressure is as you first start the engine. A gauge is not very expensive https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 (your engine has the Compucheck fitting for connection of the gauge).

I'm assuming you have a C7 based on the HP number. There is a fuel pressure regulator on the back of the head. Adept Ape (CAT Youtube guy) says these regulators fail and result in lower fuel pressure, and they are not expensive (about $30) so that may be something to consider changing (for process of elimination).

[discovery39s]

You may want to be careful dead heading the fuel pump with a gauge. Fixed displacement pumps can be damaged. I agree with the previous statements regarding air intrusion. IF there is any leak to atmosphere then the fuel will drain back to the lowest point. It is possible that the shaft seal has failed, or failing, allowing air into the system. If it was my problem then I would T off the fuel line with a gauge and watch the pressure at initial start and see if the pressure builds over time(as you have described as a delayed start). In the interest in saving time, and not waiting a month, remove the tubing to the head, allow to drain and attempt to start. If the test provides similar results to your issue then YES, you have air intrusion somewhere. Start checking all connection points and possible fuel transfer pump failure(shaft seal).
Good Luck!

[CountryB]

I'm not suggesting he deadhead the pressure.
There will be a CompuCheck fitting on the secondary fuel filter housing. Just plug your pressure gauge into it and see if there is good pressure while cranking (at least 25 to 30 psi on C7). If there is - then problem is not likely air in the fuel.

[discovery39s]

Originally Posted by CountryB

I'm not suggesting he deadhead the pressure.
There will be a CompuCheck fitting on the secondary fuel filter housing. Just plug your pressure gauge into it and see if there is good pressure while cranking (at least 25 to 30 psi on C7). If there is - then problem is not likely air in the fuel.

I aegree with that. 10-4
My reply was due to past experience with owners that did dead head pumps in the attempt to test and bad things happened.
Thanks for clarifying.

[capnj]

Thanks for the tips guys. Really appreciate the info. I started it up this past Sunday after sitting for an extra few days , started a little rough on first crank but did start. coach only has between 1/4 & 1/2 fuel so am going to fill up and see what happens.

[Gaspumpcity]

In the picture of the yellow hand primer pump when you get ready to start unscrew the pump then pump till it get real hard to pump. If no start try pumping while you’re trying to start your engine. It’s also good idea to replace the check valves in hand primer pump. Check the fuel line to the hand pump for restriction by inserting small welding rod (brass) into this line. This line when exposed to heat can grow shut. Best way to check air in the fuel is using a site glass. These are all basic troubleshooting when hard starting is present.

[Gaspumpcity]

When trying to start you said it’s a little rough like black smoke or white smoke from exhaust pipe? When your mechanics worked on it did they run injectors test? After you filled fuel tank and running fine then you could have a crack in the stand pipe allowing air in. Do you have diesel fuel in the radiator ?

[rabdnomaidx]

I have a 1999 Newmar Dutch Star w/3126 Cat that refused to start one day and I changed the I.P.R. Valve. Now it starts right up, but dies as soon as I let off the starter. I have pressured the fuel tank and it hasn't helped as of yet. It fires right up, but dies right away. the hand primer is new and appears to be pressured up. The primary and secondary fuel filters are new. Road service Cat mechanic read the codes and stated that the I.R.P. valve was likely bad, but said no other codes showed up. It is almost like the ignition switch is not keeping juice to something after it starts. Please! Any suggestions?

[teekay]

My 2006 C7 is having a similar problem. After sittting 3+ days it is difficult to start. On the initial crank it will catch, run rough then die. Then crank, crank, crank, catch, run rough a few seconds then fine. When it does start I'll get lotsa white-blue smoke. Once it is running it runs fine without smoke. This problem has been on-going since April. In June the local CAT shop replaced a fuel line check valve (location and type unknown) but problem continued. In October a well respected diesel shop said it was faulty check valves in fuel transfer pump which are part of HEUI pump. So the HEUI has been replaced $$$$. Went to start it today after a 10+ day sit and it was a very difficult start.

Any suggestions or ideas?

[capnj]

have you had fuel pressure regulator checked?

[Cat]

Originally Posted by teekay

My 2006 C7 is having a similar problem. After sittting 3+ days it is difficult to start. On the initial crank it will catch, run rough then die. Then crank, crank, crank, catch, run rough a few seconds then fine. When it does start I'll get lotsa white-blue smoke. Once it is running it runs fine without smoke. This problem has been on-going since April. In June the local CAT shop replaced a fuel line check valve (location and type unknown) but problem continued. In October a well respected diesel shop said it was faulty check valves in fuel transfer pump which are part of HEUI pump. So the HEUI has been replaced $$$$. Went to start it today after a 10+ day sit and it was a very difficult start.

Any suggestions or ideas?

Not trying upset you put your diesel shop was not correct the transfer pump and or check valves on all Heui pumps that I am aware of can be replaced without changing the complete heui pump. Things might have changed now and I haven't done one for a couple years, anyway you really need to install a fuel pressure line and gauge. And actually see what the fuel pressure is when cranking after it has sat and wont start. One of the symptoms of worn or damaged fuel injectors is hard starting after the engine has sat 2or more days. Once started it blow whitish blue smoke until warming up. After starting and warming up the engine will start normally until it sits for the couple days.

But first
1. Is your inlet heater working?
2. What is your cranking fuel pressure when the engine isn't starting.
3.Are there any diagnostic codes.
4 Try unplugging you actuation pressure sensor and see if it starts.
Do these before looking at the injector change out.

[teekay]

The coach is back at shop for "warranty work" of the HEUI reapir. Hopefully in next week we'll have correct diagnosis and fix.