Hello. We recently purchased 2007 Cat 988H wheel loader in good condition. Just prior to it shipping, the dealer realized it was taking longer to start than it should. The dealers mechanic put a vacuum on it to check for air problems as follows: As per Tec.s Comment. Machine had been worked on before for not starting after sitting for a day. vacuum tested the system, after numerous tries found what appeared to be a leak in the filter housing area. After changing the fuel temperature sensor in the housing it would hold a vacuum. We left it outside overnight, it started after the second attempt, it was quite cold. Left it for two days, went in and started after the second attempt. Stopped in the next day and it started ok again, Part # of the Sensor 256-6453. Since then the machine shipped to us and took a while to get is started to unload off the trailer. Other mechanics have looked at it and cannot seem to determine the problem. If the machine is warm or has been running, it starts ok. If the machine sits for a couple of days, it takes a long time to get it started again. Any advice gentlemen?:Banghead
I dont have much experence with the newer model 988s. But I would look at seals and the fuel system.
If you prime the fuel system before attemting a "cold" start does it fire up as it should then? You can also put a piece of transparent hose in the fuel return line and check for air in the fuel when engine is running. The check valve 281-2725 placed in the fuel filter base might be worth trying to replace, it has been known to stick and not seal properly.
This does sound like it is loosing its prime. The priming pump is a normal suspect and has cause this problem before on other machines. The electric ones are prone to corrosion and debris. The transfer pump has check valves inside and also fail or don't seat correctly and yet the engine still makes full power, only problem is hard starting. The sampling port can also allow air into the fuel system. How many hours are on the engine?
is there any smoke coming out the stack when you first start turning the engine over or does it take a while?? you might try installing a electric pump temporary inline between the tank and engine that will come on with the key. this will automatically send fuel up to the injection pump before started. this will tell you if the lift pump is bad or not. kent baugh www.ktbaugh.com
We have seen quite a few machines that the fuel return check valve sticks open like Per Eriksson said. If that is OK I have seen 1 988G that the seals on the bottom of the injectors were not sealing and would give a hard starting complain in the morning. When the engine is cold compression is getting into the fuel and causing a hard start. If you were to remove the injectors you will see most likely 1 or 2 that have a carbon track past the seal. This machine would start fine once the engine was warm but if you left it overnight you would have to crank it 20-30 seconds in order to get it to start. I would double check everything else just to make sure before you start removing injectors.
how cold is it out where your at? both our 988g and h take a while to start when its cold, ive been told by cats rep's this is normal, although we did have a leak on the fuel return line on our g, the one on the deep end of the engine compartment, nearest the walkway, behind the cab. hope this helps.
Sounds like this machine has a history of not starting. I bought a new cat loader (0 hours) and the machine would never start good when cold. Fought that machine for years, once it started it ran great. Ran it till the first overhaul and discovered it was assembled at the factory one tooth out of time.....might be your problem if all else fails.