Hard start white smoke

u2slow

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With the miles and symptoms, I'd be keen on installing a HPO gauge.

My guess is the pump is getting slow to build pressure, yet the injectors dribble in fuel before it actually starts.
 

Kraig

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The only weird part is this has happened on two different engines. I just swapped in a 225k engine and it started up well for the first couple weeks and now it's doing the same thing.

I just started it with a scanner and the fuel gauge on it. The fuel gauge was slow to build but so was the hpop. But that could be a lg in the scanner. It seems unlikely that two different engines would do that same thing. I thought maybe a fuel leak that was draining the line back to the tank and therefore having the pump to prime every start up. But apparently not. I'm confused.
 

Kraig

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This may sound crazy but what about adding a low pressure fuel pump after the selector valve to make sure I have fuel to the bowl? I am at a loss on this as I have no leaks or anything so j. Any figure in where my fuel is going.
 

greenskeeper

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With the miles and symptoms, I'd be keen on installing a HPO gauge.

My guess is the pump is getting slow to build pressure, yet the injectors dribble in fuel before it actually starts.

HPO pumps almost never fail
 

greenskeeper

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The only weird part is this has happened on two different engines. I just swapped in a 225k engine and it started up well for the first couple weeks and now it's doing the same thing.

I just started it with a scanner and the fuel gauge on it. The fuel gauge was slow to build but so was the hpop. But that could be a lg in the scanner. It seems unlikely that two different engines would do that same thing. I thought maybe a fuel leak that was draining the line back to the tank and therefore having the pump to prime every start up. But apparently not. I'm confused.

This may sound crazy but what about adding a low pressure fuel pump after the selector valve to make sure I have fuel to the bowl? I am at a loss on this as I have no leaks or anything so j. Any figure in where my fuel is going.

So... have you run the truck with the chip removed ?
 

Kraig

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Honestly I forgot. I will do that when I get back to the truck and report back. Ive had a time working on these problems as my wife has completely lost faith in my trusty ole OBS
 

Kraig

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Ok, removed chip. No change. Unplugged icp, no change, swapped out cps, no change.
Here is a screenshot of the icp and ipr during a starting event.
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Kraig

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The last one is from a really strong truck that starts as it should
 

greenskeeper

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The last one is from a really strong truck that starts as it should

I still think it's something to do with the chip, since you said the problem happened immediately after installing it. Can you get another unmolested PCM to borrow and swap in?

Also the IPR could be the issue. Just because the PCM is asking for a certain duty cycle, doesn't mean the IPR is actually doing that. I would check the pigtail leading to the solenoid on the back of the IPR, making sure that the solenoid is also snug against the body with the small nut.

Can you swap the IPR from the good starting truck as a test?

Is the HPO reservoir full prior to starting?
 

Kraig

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Hpo Res is full. I tried a pcm from an auto truck and my truck did not like that. Not at all. But it did not start any quicker anyway.
I have a sore ipr I will try that. It is just so weird because when I swapped in the new engine it ran great and slow got worse just like my old engine. But in a space of a few weeks or less. It has to be related as I know I cannot be that unlucky.
 

greenskeeper

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Hpo Res is full. I tried a pcm from an auto truck and my truck did not like that. Not at all. But it did not start any quicker anyway.
I have a sore ipr I will try that. It is just so weird because when I swapped in the new engine it ran great and slow got worse just like my old engine. But in a space of a few weeks or less. It has to be related as I know I cannot be that unlucky.

If it started the same with the auto PCM that is a fair enough test to confirm your PCM is not bad. The truck probably threw a bunch of codes for the missing auto transmission sensors.

I'm confused now. Earlier you said it started have problems after installing a chip? Now you've gone through two engines with the same problem? Which is it?

Also have you tried plugging in the truck (confirming prior that the block heater is working) for at least 3 hours prior to starting?

How quickly does the fuel pressure build at the schrader valve while cranking ?
 

Kraig

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It takes til it starts to get up to pressure. So I was wondering if I had a fuel flow prob which is why I have amassed the parts to do e fuel this coming weekend. I do have a leak in the valley of fuel but I have resealed the bowl, replaced the fuel lines and not found that stinkin leak. So at least I will have a regulated return this coming weekend. I have already assembled the stuff for the tightwad mod just to solve my fuel leak.
 

greenskeeper

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It takes til it starts to get up to pressure. So I was wondering if I had a fuel flow prob which is why I have amassed the parts to do e fuel this coming weekend. I do have a leak in the valley of fuel but I have resealed the bowl, replaced the fuel lines and not found that stinkin leak. So at least I will have a regulated return this coming weekend. I have already assembled the stuff for the tightwad mod just to solve my fuel leak.

That's your problem. Fuel pressure should be almost "instant" when cranking with a correctly working mechanical fuel pump and regulator.

How old is the mechanical pump? Has the regulator on the fuel bowl ever been rebuilt?

Personally I prefer the mechanical pump on the OBS compared to the electric on the SD (I've got both)
 

Kraig

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Honestly the mechanical pump is fairly new. As in a few months old. But if that's the issue I'm going to Do the e fuel this weekend. I hope that solves it because I am at my wits end. I love this truck and KNOW it can be reliable but these recent issues have cause at least my wife to question its position in my driveway! Not cool!
 

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