Hard Starting.

[JThorsten]

I recently bought and 03 cummins and noticed that it was getting harder and harder to start everytime. I changed the fuel filter and it made a world of a difference, but recently it has been doing it again. I tried changing the filter again but it didnt work. So I'm looking for suggestions, maybe possible weak lift pump, idk. Does the rail hold pressure after the truck is shut off?

 

[JThorsten]

It runs fine once it starts, it just cranks for a while before it starts, sry.

 

[Red_Rattler]

How long is "awhile"? Also the truck won't start until it sees proper oil pressure so ever start cycle is different than the next depending upon conditions...

 

[JThorsten]

This morning i was wondering if it was even gonna start, because it seemed like it took that long.

 

[Red_Rattler]

Is it blowin any white smoke out in the process? Any kind of fuel psi or rail psi gauge?

 

[JThorsten]

It has never smoked at all, and no i dont have any guages. Wish I did.

 

[NRussell]

your rail pressure valve is probably toast.

 

[Red_Rattler]

When you click the key on can you hear the lift pump buzzing? Also you can try capping the rail pressure relief valve, a great how to can be seen here Capping A Fuel Rail - Diesel Bombers

 

[JThorsten]

how hard, and expensive is that to fix, but once it starts it runs fine, and yes i can hear the pump

 

[Red_Rattler]

5 bucks if you have the tap already. Click the link for the pics

 

[JThorsten]

instead of tapping it i can just simply get a new relief valve.

 

[Slow Six]

When mine had a hard starting problem the fix was new injectors and cross over tubes. If there is leakage in injectors or the tubes it takes a while to build enough rail pressure for the ECM to see and let the injectors open. In my case the problem got worse and worse until I had a no start situation. This may not be your problem but it has been the cure for quite a few of us.

 

[Msilbernagel]

When my OEM fuel pump (attached to back of fuel filter cannister, like a leach) went - it didn't just 'go'... it was intermittent. I'd look there first... I don't know how many miles on your system, but you can get a kit to replace the OEM pump with a fitting (e. g. Vulcan), and then install a more reliable pump back near the tank... generally considered a better solution.

In any case, woudln't hurt to have a fuel pressure gauge so you would know... both of a failing lift pump or a plugged filter. You can tap the line between the filter and CP3.

When the rail pressure relief valve went on mine, I could also 'see' it on my fuel pressure gauge - as it looked like a plugged filter. Even with a new one, enough additional fuel was being bled off through the return to keep the pump from going above 6-ish PSI at best, below 0 under load.

Mark

 

[JThorsten]

and what kind of cost am i lookin at to fix that?

 

[sag2]

Most likely injector(s) going bad. The only way to prove it out is to cap one line at a time and compare return flow to the tank. It has been covered several times in the past and requires a couple of special tools.

 

[sag2]

From the archives:



I had a similiar problem and solved it.



My motor is an '03 HO ISB-305 installed in a Hummer H1. The truck ran fine for a year or so, then I got some bad fuel in January. I went through 3 fuel filters until it ran fine. It got progressively harder to start. Once started, it runs great. The fuel could have caused the problem, I can't be sure.



Since it ran fine, I suspected the CP3 was OK and the problem was a leaky injector. When an injector leaks badly, the rail cannot pressurize itself enough to start. Once it starts, the system (as you describe) runs fine and there is 6000psi at the rail even with a leaky injector.



I read up all I could on this and decided to buy a Quadzilla rail pressure gauge to confirm my findings.



Prior to this I checked the FCA and overpressure valve, both were fine.



Sure enough, the rail pressure during crank was 300-600 psi. You need about 4000 or higher for it to start.



A friend runs one of the 18 Cummins service centers across the country.

He's a offroader (a Jeeper) but was tickled to see a common rail in a Hummer.

He offered to have a tech look at it (as a favor).



I told the tech everything I found (sent him a long email) and we decided to cut to the chase and cap off the rail one injector at a time.



We started with capping off #1, and sure enough, the truck fired right up (I did it a dozen times). We moved the cap to #2 and the truck didn't want to start. I moved the cap back to #1 and it started right up. While you can do a leak down test, I didn't feel it was necessary. This whole test took about an hour.



I ordered an injector, it took about an hour to replace. The truck started right up.



The Cummins part # for the rail cap is #3164325 and it's about $30. I'm going to order the leak down bolt (that goes on the back of the block) so I can do further testing down the road.



A new injector was just over $300. That included a injector nozzle which I'll keep as a spare.



Now if you have several leaky injectors, this will be a bit harder to test on your own and you'll need a few rail caps and want to measure the amt of fuel coming off the back of the head.



I also stopped by another high end diesel shop and talked to their service manager. For me anyway, I found that if you've read up on how the system works, and don't appear lazy, the service managers and techs will be happy to fill in any blanks.



You can always pull all 6 injectors (not hard - 2-3 hours) and send them out for testing. Or buy a rail cap like I did and try to figure it out on your own.



Frankly, if you bought 5 rail caps and capped off all injectors but one at a time and hooked up a plastic tube to a measuring jar, you'd find out which one(s) leaked considerably. The Quadzilla rail pressure gauge (about $180) will confirm if your hard start is from a leaky injector(s)



So check the FCA and pressure relief valve, and order some caps. It worked for me. By the way, I'm not a mechanic, I write software - I just enjoy building stuff and want to know how things work since if I break down on a trail, I need to be able to fix it.



When you get your injectors, inspect each injector body for tiny cracks.



I'm going to order to special bolt that you use to replace the banjo bolt on the back of the block for measuring leak down into a glass jar. I'll post the part # when I get it.



Good Luck and post what you find. .

__________________

Your tests are accurate as you describe them, but your doing it backward by having 5 cap off tools. You only need one and a Miller 9012 adapter. You cap off one at a time and measure the return flow six times as you cap each injector. Same result and less expensive, and the same amount of work. Also keep in mind the injector may be fine, it may only be a loose connector tube.

 

[2broke2smoke]

could be his starter going south as well ...



mine went out monday acted the same way ...