1997 Dodge Truck Extended Cranking Issue

Tiny
RUFFNERY
  • MEMBER
  • 1997 DODGE TRUCK
  • V8
  • 4WD
  • AUTOMATIC
  • 125,000 MILES
Hello, I have a 1997 Dodge Ram 1500 with 5.9 engine. About 2 months ago the water pump was replaced and has been running fine. About 4 weeks ago I noticed that it was taking 8-10 seconds to start when cranking the engine. It would eventually start. I went to a mechanic and he said it was either the crank sensor or a small part in the distributor (thin circular thing). He told me to crank the engine for about 2 seconds and then stop and crank it again and see if it would start, and it did, and does that every time. If I crank it for a second, stop, and crank it again it starts right away, but idols rough for about 15 seconds and then its fine. So the mechanic replaced the thing in the distributor and the crank sensor and it is still doing it with the extended crank. I went to another mechanic shop and they told me that they would have tried the same parts as the other mechanic. They plugged a computer into the truck and said that everything is fine, but that it had an extremly low RPM when cranking. They couldnt provide me any further information. I am at wits end now and would greatly appreceiate your assistance in this matter. Thank you very much!
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Monday, June 7th, 2010 AT 10:10 AM

6 Replies

Tiny
CARADIODOC
  • EXPERT
Hi Ruffnery. Welcome to the forum. The camshaft position sensor and the crankshaft position sensor should not have been replaced or even considered as the cause of this problem. When they are defective they will cause a no-start condition. That is not the same as an extended crank which is what you have correctly identified.

You don't even have to crank the engine for one or two seconds. Just turn the ignition switch to "run", wait for a few seconds, turn it off for a few seconds, then crank the engine and it will start just as quickly. Each time you turn the switch on, the fuel pump will run for one second. You might even hear it hum. Starting right away proves that fuel pressure was bleeding down. The engine will not start until fuel pressure is high enough to spray from the injectors. When you start cranking the engine like normal, it takes longer for the pressure to build up because battery voltage is drawn down by the starter motor. The lower voltage causes the pump to run slower. Even when the engine does finally start, it may run rough until pressure has reached its normal level.

Four things can cause fuel pressure to bleed down when it is sitting. If you have the same extended crank after the engine has been off for only a minute or two, suspect a leak in a rusted spot in the fuel supply line or in a section of rubber hose. You will see and / or smell that too. More commonly it will take much longer for the pressure to bled down. There is a check valve in the fuel pump assembly and a return hose to the tank from the pressure regulator. The regulator or the check valve could be leaking but these aren't real common. On newer vehicles with a "returnless" fuel system, the regulator has been moved to the tank. The most common cause of loss of pressure is a leaking fuel injector. Sometimes the spark plugs can be removed and the wetness observed but that usually doesn't work because the fuel isn't leaking into the cylinder. It leaks into the intake manifold. It is usually necessary to remove the fuel rail and the injectors, reassemble them on top of the engine, then cycle the ignition switch to pressurize the system so you can watch for the leaking injector.

Caradiodoc
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Monday, June 7th, 2010 AT 12:11 PM
Tiny
RUFFNERY
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So, is checking the injectors something I could do in the backyard, or something that I need to go to A proffessional for?I talked to my dad about what you were saying, and he agrees 100% and said tht he knew what you meant and said that he would help me do it. Thank you for your help and assistance in this matter.
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Wednesday, June 9th, 2010 AT 8:15 AM
Tiny
CARADIODOC
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I've never actually pulled injectors myself so I can't walk you through the steps. It involves removing all of them while still attached to the fuel rail, or, ... You remove the fuel rail then reinstall the injectors into it. At that point you have to cycle the ignition switch on and off a couple of times. Each time you cycle it on, the fuel pump will run for one second to build up pressure, then you sit and watch for evidence of wetness appearing on one of the tips.

You might try running a bottle of injector cleaner through the gas tank first. That will dissolve any varnish buildup that might be causing the pintle valve in the injector to not seal perfectly.

Caradiodoc
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Wednesday, June 9th, 2010 AT 1:50 PM
Tiny
RUFFNERY
  • MEMBER
Are you saying that a bottle of fuel injector cleaner could possibly solve the problem? That would be great! I will get one tomorrow. Thank you so much for your help. As a police officer, it is unusual for me to be the one getting the help, and good help at that. Thank you.
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Wednesday, June 9th, 2010 AT 7:36 PM
Tiny
CARADIODOC
  • EXPERT
My thought is it's worth a try before you go digging deeper. If varnish has built up on the tip, it might not be sealing properly. As a very high-level Carquest trainer puts it, Chrysler has almost no trouble with injectors while GM has all kinds of problems. Chrysler uses Bosch injectors which are carefully flow-matched for even fuel distribution. The four, six, or eight injectors arrive at the assembly plant as a matched set. GM pulls a bunch of injectors out of a box and throws them in an engine. While every one is good, they flow different rates so some cylinders always run a little lean and some always run a little rich. There is a company in Indianapolis that rebuilds injectors and flow-matches them. GM products are their biggest sellers. A very common comment is the engine runs smoother with their rebuilt injectors than it did when it was new.

Anyhow, getting back to your issue, I have had the same problem with my '88 Grand Caravan for about eight years. Start and stall, restart and it runs fine. When warm and it has been sitting for more than 15 minutes, there is an extended crank time of three to five seconds. I've never put a pressure gauge on it to watch what is happening because it hasn't given me any other problems since new. The potential leaking pressure regulator is also not at all common on Chrysler products but on GM vehicles, it is common for them to leak fuel into the vacuum line and into the engine. I only had one leaking regulator in ten years of working at the dealership, and that was actually a cut o-ring on a brand new car, not a defective regulator. That extended crank was much worse though. It took up to 20 seconds before the engine would start. The pressure bled of instantly when the engine was stopped, but otherwise it still ran fine. A leaky injector may take hours to bleed the system pressure down. Normally it should hold pressure for weeks without bleeding down.

One thing you might look at and consider is if you have access to a fuel pressure gauge capable of at least 50 psi and your truck uses soft rubber fuel hoses between the frame and engine, you can use hose pinch-off pliers to block fuel flow through them while monitoring pressure when the engine is off. Pinch-off pliers are made of plastic. The blades are sharp enough to squeeze the hose closed but not sharp enough to cut the rubber. If you squeeze the larger diameter supply hose and the pressure does not drop, the check valve in the pump is leaking. That's not common. If you squeeze the smaller return hose from the regulator and the pressure holds, suspect the regulator or more likely, the o-ring around its tip. That is more likely to be a problem caused by a mishap during installation, not something that happens on its own. If the pressure still drops while the hoses are pinched off, that just leaves an injector as the culprit.

Caradiodoc
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Wednesday, June 9th, 2010 AT 9:29 PM
Tiny
CARADIODOC
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One more thing you might look into is BG Injector Cleaner. It is a soap in a pressurized can of fuel that is screwed onto the test port on the fuel rail. The truck's fuel pump is disabled, then it actually runs on this product for about 15 minutes until the can is empty. I've watched the demonstration a number of times but never did it myself. I've heard good things about the product but I think it's expensive. As I recall, there is a second step to the procedure that involves cleaning carbon from the air intake system too.

I wish I could remember more, but I'm sure a salesperson can give you a sales pitch with more information.

Caradiodoc
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Wednesday, June 9th, 2010 AT 9:36 PM

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