Q: Truck wont start on its own needs throttle to start

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I have a 97 cummins 12v that wont start on its own i have to give it throttle to start if i dont it will fire but not stay running when i get the truck to run it will stay running but bog down here and there also when i put it reverse or drive it will also bog down and almost stall at some times it just started to happen my engine temps rise quickly and if i let off gas it will cool down fast. i wanna know what is causing my truck to bog and why do i have to give it lots of throttle to keep it running the truck also has a small oil leak in timing cover.

My car has 303859 miles.
My car has an automatic transmission.

Hi and thank you for contacting us. There are 4 things that could cause a problem with starting and bogging of a diesel engine. First, you will need to check the air filter. Unlike gasoline engines, diesel engines require a mass amount of air to create the compression ignition. A dirty air filter will cause the engine not to start unless more fuel is forced into the cylinder. Also the dirty filter will restrict the air flow during operation. Secondly, check the fuel water separator and drain off any water in the system. If you cannot drain off the water, then you would need to replace the filter. Excessive water in the diesel will cause the engine to run too cool and may cause a no start problem along with a bogging issue. Thirdly, you can check the glow plugs to see if they are energizing before start up.

If you are in a cool climate and the glow plugs are not working properly, then the engine will take some time to warm up. This can cause a no start situation and loss of power or bog down when throttle is demanded. The last thing you would need to do is check if your traction control is active and engaging the brakes. Sometimes, the traction control acts up and cause the brakes to come on when they are not to engage. This can cause the load applied to the engine when putting the transmission in drive or reverse. If you have checked all of these issues and still have the same problem, then the fuel pump may be failing.

As far as the timing cover leak, you would need to look to see where the leak is coming from. Most of the time, the timing cover leaks due to an old aged gasket, front crankshaft seal leaking, or the vacuum pump is leaking onto the cover. I would recommend power washing the front cover and then recheck for leaks. For further help, I would have an expert diagnose the hard start and loss of power problems firsthand in order to have this corrected.

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