Lift Pump Delay

[Texas CTD]

https://www.youtube.com/watch?v=pMS1xoZAgBE

 

https://www.youtube.com/watch?v=pQMuTYw_G8g

[notlimah]

So I guess it's possible you have a sticky relay. Although I think the relay would fail altogether before constantly sticking and giving you the symptoms you're seeing. But could be worth a shot since it's a lot cheaper then an ECM.

 

Maybe if someone could explain how exactly the ECM talks with the loft pump and how that works in conjunction with the WTS light it'd help us understand your issue better. 

 

Like on a cold start up what should you see as far as WTS light, fuel pump prime, how many amperes are being sent to the pump and both key and, cranking and then start? Anyone have that info?

 

I found this thread on CF and it's slightly different then what you're experiencing but it's similar and there's some good discussion. 

 

Maybe @KATOOM can drop some knowledge on us!

[KATOOM]

Open the hood and in the power distribution center, use the test light to confirm the function of the injection pump relay.  You want to know if the injection pump relay is powering properly during engine cranking.

 

Yes, the delayed power to the fuel pump is odd but knowing that the VP doesnt require fuel pressure in order to start the engine has me wondering why you have to crank for so long on a re-start situation.....even though the fuel pump is seemingly not pumping or is delayed.

 

That said, how's the corrosion under your hood?  You could have a bad ground.  And wow.....your fuel pressure builds very slowly.  Is that normal?

[Texas CTD]

3 hours ago, KATOOM said:

Open the hood and in the power distribution center, use the test light to confirm the function of the injection pump relay.  You want to know if the injection pump relay is powering properly during engine cranking.

 

Yes, the delayed power to the fuel pump is odd but knowing that the VP doesnt require fuel pressure in order to start the engine has me wondering why you have to crank for so long on a re-start situation.....even though the fuel pump is seemingly not pumping or is delayed.

 

That said, how's the corrosion under your hood?  You could have a bad ground.  And wow.....your fuel pressure builds very slowly.  Is that normal?

Thanks for responding. I will check the relay's operation. 

 

Corrosion is minimal, just dusty. 

 

I had the needle valve on the gauge closed too far. If I crack it open, I get instant 20 psi.

 

Today the truck sat on level ground for 8-9 hours. I pulled the FASS relay to make sure the pump wouldn't prime when I turned the key, then I put the relay back in, and the truck fired up instantly, with no priming, after sitting all day. I doubt it's losing prime, causing the hard start. I will park it up hill to verify that though.

 

[KATOOM]

Whoa.....  OK, with what you just said, is the extra cranking ONLY taking place when the engine is at operating temperature?  Because pulling the FASS fuse will have zero affect when the engine is cold.  Knowing this will certainly help pin point your problem.....

[dripley]

8 hours ago, Texas CTD said:

Thanks for responding. I will check the relay's operation. 

 

Corrosion is minimal, just dusty. 

 

I had the needle valve on the gauge closed too far. If I crack it open, I get instant 20 psi.

 

Today the truck sat on level ground for 8-9 hours. I pulled the FASS relay to make sure the pump wouldn't prime when I turned the key, then I put the relay back in, and the truck fired up instantly, with no priming, after sitting all day. I doubt it's losing prime, causing the hard start. I will park it up hill to verify that though.

 

Just so I understand you pulled the relay and just turned the key on, then replaced the relay and started the truck? All this on a cold engine.

[notlimah]

Yea I had the same question as Dripley. Trying to figure out what your troubleshooting process was.

[Texas CTD]

10 hours ago, dripley said:

Just so I understand you pulled the relay and just turned the key on, then replaced the relay and started the truck? All this on a cold engine.

 

6 hours ago, notlimah said:

Yea I had the same question as Dripley. Trying to figure out what your troubleshooting process was.

 

Correct dripley, in that order. 

 

Sorry if I wasn't clear.

 

Just did the same process a minute ago, after the truck sat for 24 hrs. Started right up.

[KATOOM]

So just I'm understanding your situation.....

Your truck starts fine in the morning, or when the engine is cold and has been sitting.

But when the engine is at operating temperatures and you attempt to re-start the engine after a fairly quick shutdown (like the gas station or store), it will hard start (extended cranking).  This is probably more problematic when the ambient temperatures are hotter as well.

Also.....this all started pretty much right after the FASS was installed.

 

If all this is correct then it clearly sounds like the VP fuel solenoid and rotor timing ring are objecting to the increase in fuel pressure upon engine cranking when the engine is warm.  Not uncommon as the tolerances change when the VP is hot and those solenoids require at least 9 volts to function properly.  When combined with a higher pressure/volume fuel pump, these sensitive components freeze up until the overly high cranking pressure purges.  Trouble is the only thing you can do to stop the pressure problem is install a delay relay which will cut the power to the fuel pump when the ignition is in the START position.  Doing so will stop the fuel pump from pumping while cranking the engine, and as long as the prime is retained, the VP prefers this.  You DONT want to turn down the FASS because then the overall fuel pressures will be lower as well.

 

As for why you have a delay in fuel pump reaction, did the FASS come with a new wire loom and relay?  Hopefully it did which will remove the added amperage strain from the aftermarket fuel pump.

[Texas CTD]

59 minutes ago, KATOOM said:

So just I'm understanding your situation.....

Your truck starts fine in the morning, or when the engine is cold and has been sitting.

But when the engine is at operating temperatures and you attempt to re-start the engine after a fairly quick shutdown (like the gas station or store), it will hard start (extended cranking).  This is probably more problematic when the ambient temperatures are hotter as well.

Also.....this all started pretty much right after the FASS was installed.

 

If all this is correct then it clearly sounds like the VP fuel solenoid and rotor timing ring are objecting to the increase in fuel pressure upon engine cranking when the engine is warm.  Not uncommon as the tolerances change when the VP is hot and those solenoids require at least 9 volts to function properly.  When combined with a higher pressure/volume fuel pump, these sensitive components freeze up until the overly high cranking pressure purges.  Trouble is the only thing you can do to stop the pressure problem is install a delay relay which will cut the power to the fuel pump when the ignition is in the START position.  Doing so will stop the fuel pump from pumping while cranking the engine, and as long as the prime is retained, the VP prefers this.  You DONT want to turn down the FASS because then the overall fuel pressures will be lower as well.

 

As for why you have a delay in fuel pump reaction, did the FASS come with a new wire loom and relay?  Hopefully it did which will remove the added amperage strain from the aftermarket fuel pump.

No sir, that's not really the situation. I'm aware of hot hard starts with after market fuel systems, and my issue is different.

 

Temperature, both ambient and engine temp dont affect starting the truck. 

 

This lift pump key-on delay began about a year after installing the complete FASS kit with harness and relay. 

 

I randomly get a delay of the prime sequence, which has been traced back as far as the stock lift pump harness, which should rule out any FASS problems. I've used a test light at the stock lift pump plug, and the ecm does not provide power,  until 4-5 seconds after the key is turned on. But it only acts up 50% of the time. 

During the delay, before the pump primes, if I try to start the engine, it cranks over for several seconds, creating a hard start. (See video a few posts back)

 

I think I ruled out the hard start being caused by a loss of prime, with the procedure stated a couple posts above.

 

Sorry if we're going in circles, but I haven't had time to do any more diagnosis. Thanks for all the help so far.

[KATOOM]

2 hours ago, Texas CTD said:

Correct dripley, in that order. 

 

Sorry if I wasn't clear.

 

Just did the same process a minute ago, after the truck sat for 24 hrs. Started right up.

 

21 hours ago, Texas CTD said:

Thanks for responding. I will check the relay's operation. 

 

Corrosion is minimal, just dusty. 

 

I had the needle valve on the gauge closed too far. If I crack it open, I get instant 20 psi.

 

Today the truck sat on level ground for 8-9 hours. I pulled the FASS relay to make sure the pump wouldn't prime when I turned the key, then I put the relay back in, and the truck fired up instantly, with no priming, after sitting all day. I doubt it's losing prime, causing the hard start. I will park it up hill to verify that though.

 

OK then that kinda rules out everything you just said above.....

 

So go back to when I said that the VP will start with no fuel pressure during cranking as long as the prime is retained.  Where this is obviously not a prime problem is because you can shut down and immediately have the extended cranking per indicated in your videos.

 

But in knowing this, if the prime is fine and the problem is not a result of the FASS pressure, as you say, then the engine shouldn't suffer from extended cranking but rather fire right up.

 

Since its not, this brings me back to where I suggested getting in the PDC and confirming with that test light that the VP relay is actually getting power when you're trying to start it.  Because it seems like its not, and maybe its delaying as well.

 

And again, what can cause such odd anomalies is either failing components or bad connections or bad grounds.

[Texas CTD]

That's my next step, to check the VP44 relay. I haven't had time.

[dripley]

This is to much like a delayed WTS. It has to be related to that.

[notlimah]

Yea this is a tricky one because it has some common signs of known issues but it's a mix from multiple different things. 

 

This has electrical issue written all over it. Doesn't seem mechanical to me. Hopefully testing power to the VP will clear things up!

[Texas CTD]

On 7/13/2016 at 11:52 PM, dripley said:

This is to much like a delayed WTS. It has to be related to that.

Dang if you aren't right. 

 

I had a few minutes (in the dark) to look at the truck. Tested for power in the PDC at the VP relay. Power delay is the same, just like with the lift pump.

 

And I feel like a real dumb@ss. I never payed attention to the WTS light. My scangauge was blocking it, so I couldn't see it.  

 

It is indeed,  a delayed wait to start. 

Not every time though, like I've mentioned before.

 

The obd on this truck have never cooperated. I have 4 codes, but can only read a couple of them. 1689 from unplugging the relay. 0234 from overboost. Obviously 1693, but I can't read the 4th code.

[dripley]

Sounds like you found the problem. Now what to do about it.

[Texas CTD]

17 hours ago, dripley said:

Sounds like you found the problem. Now what to do about it.

 

Check grounds first.

 

Find out what the other code is, out of curiosity.

 

Keep an eye out for a good used ECM.

 

Drive it til it quits.

 

Sell it and buy a 12 valve.  (joking)

[dripley]

Sounds like a plan. If you plan on keeping the truck an ECM from Cummins or even the dealer is another, yet much pricier way to go. The used ones are getting older every day and the internet rebuilders scare me. Went that route once, very bad experience for me.

 

But I would want to check things out first as you state above before dropping that kind of coin.

[notlimah]

What's a brand new ECM go for these days?

[dripley]

i dont know of any new ones being available any more. Even the one that I got near 5 years ago was a reman from Cummins. It cost me $1400 with programing and install. At the dealer then they were well over $2000.