My 98 dakota 5.2 (90,000) will not start up first try unless I hold the key on and wait through alot of cranking after it has sat for over an hour. If I only crank for a second or two, then wait to hear the fuel pump shut off, it'll start right up on the second try. I also have felt a pulse in the fuel rail during idle and can hear a ticking (sounds like from the same side the fuel was pulsing on) when driving, mostly when accelerating it gets pretty loud. Has anyone heard of this or have suggestions about what I should look into replacing? I read somewhere about the IAC may be bad but would like to other input. Thank you!

 

There is a check valve in the fuel pressure regulator that goes bad. The fuel pressure regulator is part of the fuel pump assembly. One way to test is after the truck sits overnight or for a few hours turn the ignition key to run but don't start the engine. Let it sit with the key in run for 15 seconds or so and then turn the key to start. If it starts right up that is a sign the fuel pressure regulator valve is definitely bad. You can also get a cheap fuel pressure gauge at Harbor Freight Tools or maybe a parts store and check the pressure in the fuel rail if your fuel rail has a test port. I don't know if the 98's or the 5.2's have one. The Haynes book has the specs to check the fuel pressure.

The noise you hear could be the fuel pump itself going bad. They will sometimes sing a death song before they quit altogether and leave you stranded somewhere. From what you described it does not sound like a bad IAC valve. The fuel pressure regulator on my truck did the same thing, would not start unless I cranked it for 10 seconds or longer. I got a new fuel pump at Advance Auto Parts and it has been fine ever since.

Jimmy

 

Yes there is a test port, I saw it yesterday when I asked a buddies dad about the issue. He said the same thing about the check valve and is bringing a tester today to try that out. I've tried to turn on the key without starting and waiting about 10 seconds or so but still no start, it does the same thing as if I didn't do that. I can hear the fuel pump when it's idling (the little whine it has) but what I'm hearing almost sounds like an exhaust leak, how they go tick tick tick tick, but still have had no luck finding that leak either. Just to clarify, buying a new fuel pump will include the regulator which obviously would have a new check valve in? Can I just buy the regulator or would I be better off just replacing the whole pump? Thank you for knowledge and quick response.


Chase

 

Fuel pump, pressure regulator and fuel filter are all parts of the pump assembly. The only part on the pump that can be replaced separately is the fuel level sending unit, for the fuel gauge in the dash. The fuel system tester will tell you if you have problems with the fuel pump.

I don't have much idea what the tick noise could be. You could remove the IAC anyway and clean it. Handle it very gently, don't drop it. Clean the pintle end with a shop rag soaked in carb cleaner. You just want to get the crusty crud off the pintle end. Clean the IAC orifice on the Throttle Body and lube the orifice O-ring with a little clean motor oil.

You might want to use a volt meter and check the Manifold Absolute Pressure sensor and Throttle Position Sensor too and be sure they are reading correctly and giving correct info to the PCM. The Haynes book will also tell you how to test them.

Jimmy

 

Ok, I'll have to pick up the Haynes book and test those senors and seems more than likely have to replace that fuel pump assembly (****ty) but now I have a better idea of what is wrong with this problem child. Thank you once again, you've helped out alot.


Chase

 

I have a similar problem on 2001 / 4.7 eng. 56000 miles. Changed plugs & air filter, cleaned AIS and throttle body.

Any more suggestions

 

I put a fuel pressure tester on the fuel rail test port. When the truck was running, the needle shakes alot but stays around the same pressure. Once i shut off the truck the pressure drops basically all the way down, holds maybe 5 psi if I'm lucky. So with this happening, I can shut off the truck and start right back up no problem, up to about a half hour. Anything after, the system has totally lost pressure and must either crank a lot to get started or mutiple are needed and I'll be saying bye to my starter too. I'm going to replace the fuel pump assembly because it is more than likely the pressure regulator that is out and it is a all-in-one type thing. Hope this helps ya out!




Chase