I have a problem with my truck when it gets hot during the day, it will not start on the first or second try. It will usually start on the third try. After setting all night it will start normally which is only a click of the starter. It seem to be related to the heat of the day. If the day is not as hot as usual, it will sometimes start on the first try or maybe the second try.

I have checked all of the simple things that I think could effect it. It is setting no codes. Once the truck is running it runs normally with nothing out of the ordinary. The last few days the high temp has been close to 100. Today has been in the low 90’s and the truck has not acted up as often.

The VP44 was changed about 3 years ago or about 35,000 miles. Recently put in 2 new batteries. Total miles on truck about 165,000.

Has anyone had this problem and what did it take to fix it.

Any suggestions will be appreciated.

Daniel

 

The issue could be caused by a couple different things. First off, whats your fuel pressures? Have you added an aftermarket fuel pump or are you still running the OEM lift pump?

 

Lift pump has been replaced twice and pressure is currently normal.

Daniel

 

I need to know what your fuel pressures are. "Normal" doesn't help me since what the dealer calls normal and what the "right" fuel pressure is will be two completely different figures. Sounds like you've been having a dealer fix your truck and the OEM lift pump took out the first VP and then they kept replacing the garbage OEM lift pumps which are unreliable and cant supply the VP with enough fuel/pressure and now the VP computer (PSG) is showing signs of heat cycles.

 

First of all, I am doing all the repairs to my truck including installation of the VP44.

As to normal pressure, I am referring to what has been normal for my truck. When the last lift pump was installed it was running about 14psi and dropped to about 12psi almost immediately. It it is still running about 12psi. These pressures are taken with the engine at idle. I have a gauge that I can hook up easily at the outlet of the fuel filter canister.

I understand that you are saying the volume may not be enough to keep the VP44 cool, since it is cooled by the fuel from the tank.

What would be your suggestion to solve the lift pump problem? I have considered some of the more expensive setups, however some people have reported regretting putting them in because they did not solve the problem. Many have reported that the installation of the pump in the fuel tank did not last very long.

My original post implied that the Vp44 was installed at 35,000 miles. This is incorrect, it was installed about 35,000 miles back or at about 130,000 miles.

Further suggestions will be appreciated.

Daniel

 

I would suggest a fuel pressure gauge and a new aftermarket lift pump. I run the FASS ddrp=02 and it gives me 17 psi at idle and 15 cruising. the fuel cools and lubes the vp44. Are you running any two stroke to offset the low sulfur diesel?

Also, it is recommended to have fuel pressure at a minimum of 14 and a max of 20.

 

I can appreciate your concern..... If the VP was installed at about 130k odometer miles and has been on there for only 35k miles then thats good news, but unfortunately because you're having hot start issues thats not good. If you would have said that you recently installed a FASS or Airdog or something like then I'd say the problem was cranking pressure from that new fuel pump but since the OEM lift pumps are "rarely" capable of supplying enough fuel pressure at all, let alone too much fuel pressure, your problem is most likely that the PSG is showing signs of too many heat cycles and is probably going to fail. When?.....I have no idea. Maybe a month, maybe a year. The next time you're experiencing the hot hard start, try pouring a few gallons of cool water on the top of the VP to cool the PSG down. If it starts more normal when the PSG is cooled then there ya go.

As I mentioned before, the replacement VP you have is probably an OEM off the shelf unit or its a poor quality re-manufactured unit with a reused PSG computer instead of a new PSG. A quality re-manufactured VP from a reputable vendor is highly suggested as then you should have a VP which will last. That said, you still need to supply that new VP with ample fuel volume and pressure. No less than 15 psi at all times. Will a good fuel pump the idle psi will be around 18-19 psi and the WOT psi will drop to around 15-16 psi. The best pumps for this are the electric FASS pumps or the mechanical Fuel Boss pump. Pureflow pumps (Airdog, Raptor) used to be quality but the company sold out a few years ago and the number of problems reported from their poor quality pumps would keep me from getting a Pureflow pump. You'll see I have a Raptor but its around 5 years old and before the sell out took place.

As for fuel pumps and VP reliability..... Just because you install a quality fuel pump to supply the VP doesn't mean that the VP will last forever. Matter of fact, the odds are that someone installed their new fuel pump many miles and years after that VP was subject to lots of time supplied by an inadequate OEM lift pump. So basically the damage has been done and a new FASS isnt going to save anything but maybe prolong the failure for awhile. How long?.....that would depend on prior fuel pressures. Its not uncommon for some to post a question asking why their VP failed right after the aftermarket fuel pump.

Also, there can be untold reasons why a VP failed besides the common too low of fuel pressures. You should NEVER run out of fuel. You'd be surprised how often that happens and when it does its very bad for the injection pump. That goes for ANY fuel injection system but especially bad for the VP. And you should try not to run the fuel levels in the tank lower than around 1/2 tank during the summer in order to reduce fuel temps. And running a lubricating additive like 2-stroke in the fuel is highly recommended. Around a 250:1 ratio (pint or so) of the Walmart stuff or any recommended fuel additive per fill up. Note that not all diesel fuel additives are good lubricants.

In saying all that, there is other reasons for hot hard starts. Batteries or starter condition for instance. You replaced the batteries so hopefully they're in good shape. Not terribly uncommon either for a battery to be bad right off the shelf. Also, the OEM starters are very stout but as soon as people have issues with starting they run out and get a "lifetime replacement" starter from the cheapo auto parts store. Those starters are garbage and will generally never last and possibly crank slower as they drag. That means that the engine will have a hard time starting as proper crank speed is very important with diesels since they require compression temps in order to achieve proper combustion. Cranking too slow will cause a hard start. But if you have the OEM starter then thats not likely your problem.

 

I am running 2-cycle oil in the fuel.

I have also ran water over the IP with a water hose when I expected it would not start properly. I ran it for a while or until I felt like it would have to been cooled enough and it still was hard to start. Started on the third click of the starter which is the normal times when it is very hot. Sometimes when it is hot it will take four times to start.

As to the starter cranking too slow, I do not have that problem with my truck.

Daniel

 

Slow starters are difficult to notice since it only takes 25-50 rpm less starter speed to cause starting issues. Like I said, if you have the OEM starter then very likely thats not the problem. But if you have a parts store replacement starter then I'd consider looking at swapping it out.

On a last ditch effort, you "can" try disconnecting the lift pump when you experience the hard start. If by chance it does start normally then I have a solution for you but just note that you have a very rare case.

Also, because you still have the OEM lift pump you'll have to reach way in to the ECM plug at the lift pump to disconnect the fuel pump. And.....if it does happen to start normally then you'll need to shut it down asap and re-plug in the fuel pump otherwise you'll harm the VP running without fuel pressure. Let me know if that works too.

 

I do not believe it would start with the lift pump disconnected. Here is the reason why, when it is not starting on the first hit of the starter, if I let the lift pump run the 25 seconds after the first no start, then it will start on the next try.

I do not look forward to unplugging the lift pump on a very hot engine. However I would be interested in knowing your "very rare case" solution if I did encounter this issue later on.

Daniel

 

This is why you need to try if you're wanting to know what the true problem is.....

If it didn't start with the LP unplugged then you have a PSG problem because the only other reason it wouldn't start with the LP unplugged is if the fuel system lost its prime from a leak somewhere. And if you had a fuel/air leak then your hard starting would be more apparent in the morning or after the truck has been sitting for a day.
But if the hard hot start is caused by over-pressurizing the VP during engine cranking then unplugging the fuel pump will allow it to start normal. The reason running the fuel pump for a length of time or continually cranking the engine gets it started is because the rotor lock or the lack of pintle valve movement is finally overcome and the engine starts.
The reason cycling the fuel pump over and over help it start when there's a PSG issue is because the flowing fuel is cooling the circuits.

Point being.....there's only so many "easy and cheap" ways to diagnose problems. After that you'll be throwing money at it in parts trying to figure it out.

 

KATOOM, Thanks for your reply.

I had previously decided that I do not have a leak or drain back problem for the reasons you stated. The truck always starts normally after setting overnight.

As to the lift pump over pressurizing the VP, I do not think this is very likely because the Lift pump and VP have worked together very well for over three years at the current pressure. Since my pressure is 12psi idling at the outlet of the fuel filter, I do not think I have too much pressure at startup.

I am about to give in that I have to replace the VP44 again.

I have found a rebuilt pump at DIESEL AUTO POWER in Layton UT. that claims new electronics and steel housing for the price of $995.00. This is the best deal for one with new electronics that I have found. Do you know anything about this company?

Daniel

 

There are a few VP suppliers who not only sell quality pumps but they have their own Bosch test bench and build the pumps they sell. Here's a link which may help you out: http://articles.mopar1973man.com/2nd...ump-rebuilders I've heard good things about Industrial Injection.