Here is a new one for me.Drove home in 100 degree temps with the air going. Our 3126 Cat never gets hot, or runs hot period.Backed in the drive with the engine running. Got out opened the shop, backed it in, jockeyed it around a few times.
Shut her down. Went back and opened the engine door to look for any leaks. There were none (I previously had one). Looked at the coach, thought I would move it over a bit, all within 10 minutes. Got in, cranked perfect,. but no Start. Tried it again, good cranking, no start. Waited about 10 minutes max, cranked over and started immediately as always.Kind of makes one feel uneasy, like, "well when will it do this next when I am not at home"
My theory is, even though it wasn't overheating, but because it was extremely hot, when I shut the engine down, the engine temp went up temporally, which is normal, and the over temp sensor kicked in, till it sat a minute.
Any one else have this exciting adventure before? I am pro-active!
Thanks
Chris
Chris,
With the 3126 and a no start with good cranking speed, first thing I would do is verify that you don't have a fuel issue.
Next time this happens, go back and operate the manual primer pump. It should be very HARD to operate. If easy, that means fuel pressure has bled off. Could be the check valve in the back of the head (front of coach), could be an air leak into the fuel system.
Thanks Brett, a friend said the same thing, may have bubbled a bit, got some air. It was hot out....Great advice.
A little more detail:
If the manual pump is easy to pump, there IS air in the system or the check valve is hanging open. Pump until hard. Then try a restart.
And, if the fuel lines on that vintage coach are original, you are likely on borrowed time. If air is visable in the primary fuel filter clear bowl, you already have your answer-- air from an "up stream source". Cracks in the fuel lines are often hard to find, as the lines are on the suction side of the lift pump, so rare for fuel to leak out, common for air to leak in. Could also be an oring/gasket on either of the filters.
The other thing that can happen with any source of air getting into the fuel system is that it "opens" the system. So, fuel will flow toward the open end of the system. If the level of fuel in the tank is lower than the "open", fuel can drain all the way back to the tank. That can mean a lot of air.
Fuel line to the filter from the pump has been replaced. Old one is still hanging there fittings and all.Must have been an issue with PO. I serviced both filters around 1000 miles ago. No black junk or anything in bowl, clean as a whistle. Good info, thanks
Chris
I've seen a couple of things besides what Brett has addressed. A fuel cutoff solenoid might be sticking because of heat soak. Lesser possibility that I have seen with some diesels is a contaminated filter not allowing fuel to pass through but after the coach sits, the contaminates settle to the bottom and it starts fine but looses power on grades.
Hand pump has "O" rings that may have broken if the hand pump does not work.
Low fuel pressure can cause injection pump damage or failure.
Any difference from full to partial tank?
Our generator fuel hose had a million tiny leaks and caused it to quit after a few minutes. Easy to replace in just about 15 minutes (but not as shown on YouTube) on our 1993 U300. Engine line is harder, a lot harder. I'm thinking about using a 3/8" soft copper tubing available in 50 foot rolls for about $60 inside of a polyethylene flexible split tubing. Conventional fuel hose used on each end. https://www.usplastic.com/catalog/item.aspx?itemid=25117&catid=1051
Pierce
Yup, as I mentioned, bowel was clean as a whistle when I serviced it.
Power is fine, full or 3/8th tank. No issue there. I actually thought of the fuel shut off valve 1st thing too when it happened.
That failed on my Dodge PU once.As a tech, a customer had a bad ground on a brand x coach, which caused it to shut off intermittently.
Chris
Pierce, that's why I paid Cabin Diesel to replace mine. They have a couple of young, skinny guys that made short work of it.
In my case, the generator lines were the first to go. I had evidence of fuel under the generator, and it would run for a few minutes, then shut down as if it was out of fuel. Turned out that the generator didn't have sufficient fuel to keep going, even though the fuel tank was clear full.
I've got a five minute test for the generator hoses. It requires little mechanical skill, only running a short fuel hose to a gallon container. PM for description.
Pierce
If the fuel lines are original rubber the ULSD kills them dead. Plus the WINN fuel filter is a known problem child. Been there
Don't have a WINN fuel filter, but yes, was an issue a few times when servicing them.......Probably going to do the fuel lines in the fall, before we head south.
Thanks
Chris
Yup, they be cracked.....next on the list.....Piece of cake
Finally, problem resolved:
It was the solenoid at the dash. Went and filled up fuel, ran great, got home, shut it off no start. Checked at relay in bay with key on, had power. Pulled plug to injection solenoid, had power when cranking. Plugged it back in, it started at the rear?????
Went to front, no start at key. Went to solenoid at dash, power drops out when key is turned to start!...Bingo. Have 2 or three of those on hand. How can something so simple, be so stupid.
Here's the good news:
We have new fuel lines
We have a rebuilt return fuel line check valve
I have a spare Injector activation pressure control valve on hand (noted to go bad)
I learned so much about my coach wiring, and engine dynamics
The Cat RV hot line is awesome
This web site is awesome
Brett is awesome
Most of all my wife is really awesome and supportive.
Thanks to all
Chris and Tammy
BTW, here is what the Injector activation pressure control valve does.:
It controls the oil pressure to the fuel pump, which control's the fuel pressure to the injectors. So in reality, it is/isn't a fuel shut off valve.When it cuts the oil pressure to the pump, it stops the fuel pressure to the injectors. Only difference is, it's activated by the ECM which has to see the correct engine temp along with the correct engine oil pressure, before it powers up.
Valve is $244.00 New at Cat
$150.00 rebuilt exchange at cat
Aftermarket as shown, $75.00 delivered