Hot no start update

jeepdan · **Posted:** Sat Dec 31, 2011 6:23 am

nursecosmo wrote:

Do you have a lift pump installed?

Yes, Airtex E7181M installed a month ago. Started having hot starting issues as soon as lift pump was installed, but pulling the lift pump fuse does not help or change anything now and air is still leaking past tank connectors with pump off.

racertracer · **Posted:** Sat Dec 31, 2011 7:26 am

Is the airtesx lift pump a flow thru lift pump?

When you pull the fuse, does the lift pump continue to allow fuel to flow thru when it is electrically turned off?

nursecosmo · **Posted:** Sat Dec 31, 2011 12:07 pm

Well if your trouble started as soon as you installed the pump in the tank I'd look to the fuel supply system before even considering the other things you have mentioned. Wasn't it determined that the Airtex E7181M had too much pressure? It could certainly be causing some sort of funkiness with one of the fuel supply solenoids by over-pressuring during cranking.

Another thing which I have experienced (only in hot weather) is fuel boiling when hot. If the fuel system check valve isn't functioning, it will make an air bubble within or close to the IP and the fuel will be pushed back down the line towards the tank. They tend to do this with winter fuel which has too many light volatiles.

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

Since Jeepdan and I are having the same problem, I will share that I installed a lift pump (Oem dodge 3500 truck) to get rid of the air in my fuel system. I replaced the fuel filter head first and still had air.
Solid pressure at the fuel head after the lift install and no leaks anywhere. Recommendations from the board led me to the install of that particular pump. My hot start symptoms were happening prior to pump install.

racertracer · **Posted:** Sat Dec 31, 2011 4:33 pm

To eliminate the fuel pump as being the source, try running the engine on a separate container of diesel?

Disconnect the fuse to the in tank pump.

Fill some fuel in a plastic jug and let the fuel head pull from the jug...... see how long that lasts.

jeepdan · **Posted:** Sat Dec 31, 2011 5:56 pm

Thanks to all of the input, this website is priceless.

To recap the last two months; My problem started out as a long crank time when cold. Purging the air on a daily basis before starting seemed to eliminate it, Although one morning later on, it didn't want to start until the fourth crank and I'm pretty sure that I had expelled any air from the filter head, :?:

After a month, I decided to go with the Airtex in tank pump Mod. From the first test drive I have had sporadic problems starting up again after shutting off hot. Kieth at GDE theorized that the 15 psi. lift pump pressure is way too high and might be causing an imbalance in the valving of the CP3.
So I removed the lift pump fuse, but found no change in the problem. Could the lift pump made a sticking pump valve worse, I don't know. :?:

Then I started looking elsewhere. After finding the the Fuel Pressure Solenoid leaking off during cranking while hot, I replaced it, there was also brown rust on the low pressure section of that solenoid. Haven't confirmed yet whether the new solenoid is still leaking off causing a problem.
Fuel Injector Quantity Leak Off tests were fine although I had no way of confirming that the fuel rail pressure was acceptable during tests. :?:

As for the Airtex E7181M, it is a flow through design, It would be interesting to do a survey from the members of Lost to find out the number of pumps installed and how well that they are doing.
Sir Sam, has yours been doing well in the short term?
Do to the very sporadic nature of this problem it is very difficult to do any conclusive tests. Being able to read the fuel rail pressure would be a very big help.

jeepdan · **Posted:** Sat Dec 31, 2011 7:23 pm

As for the rebuilt CP3 pump? There is no turning back now, it has been ordered and on it's way UPS. I should have it Thursday and hope to have it installed by Friday evening if all goes well. Keeping my fingers crossed, It might be an $800.00 mistake that we can all learn from. :oops:

KhakiCRD · **Posted:** Sun Jan 01, 2012 4:34 pm

How does the engine cut off the fuel when it doesn't receive a signal from the crank position sensor? Does it send the fuel out of the fuel pressure solenoid not allowing it to build enough pressure? I am wondering if you should try a new crank sensor. It is next on my list.

jeepdan · **Posted:** Sun Jan 01, 2012 4:58 pm

KhakiCRD wrote:

How does the engine cut off the fuel when it doesn't receive a signal from the crank position sensor? Does it send the fuel out of the fuel pressure solenoid not allowing it to build enough pressure? I am wondering if you should try a new crank sensor. It is next on my list.

I don't know whether the ECM would shut the injectors down or go into a limp mode.
The ECM needs the crank sensor input to monitor engine RPM for injector timing and duration, it even monitors the speed of each individual cylinder and adjusts accordingly to smooth out the engine if a weak cylinder is noted.
With your jeeps issue of shutting off while running, the crank sensor might be suspect. But I would think that you would get a check engine light with a trouble code stored.

jeepdan · **Posted:** Mon Jan 02, 2012 6:45 pm

racertracer wrote:

Is the airtesx lift pump a flow thru lift pump?

When you pull the fuse, does the lift pump continue to allow fuel to flow thru when it is electrically turned off?

I may have to correct myself in saying that it is a flow through pump :oops:

I was going by assumptions from reading here.
I was checking out the extra Airtex 7181M that I have on the shelf today for check valve action, as well as being able to suck air though with my mouth. YOU CAN'T. :shock:

With stronger vacuum applied with a hand held pump you can get it to flow through with effort, along with a humming noise. I would have to say that it is will flow through for emergency only. I'm not sure how much vacuum I had on the system trying to drive without the pump running, certainly enough to leak air in at the quick connectors.

papaindigo · **Posted:** Tue Jan 03, 2012 7:49 am

The Airtex is an in tank pump or what I'd call a "pusher" pump not an in line supplimental pump like a Facet or Kennedy. The latter are designed with the expectation that there is another pump in the system, usually at the engine but not always (remember old engine designs especially gas involved a mechanical cam driven fuel pump on the block), so it's a good design feature for them to fail in a flow thru mode such that the other pump can continue to supply fuel. An intank pump is usually all there is in the system so no reason to design it as a flow thru so that doesn't surprise me.

I suspect the humming you heard was the pump's internal electric motor "trying" to turn as the vacuum mechanically rotated its impeller. On a true flow thru pump, at least on the Facet, there is a check valve to prevent fuel reverse flow but flow in the forward direction is virtually unrestricted if the pump is not working.

jeepdan · **Posted:** Tue Jan 03, 2012 5:03 pm

papaindigo wrote:

The Airtex is an in tank pump or what I'd call a "pusher" pump not an in line supplimental pump like a Facet or Kennedy. The latter are designed with the expectation that there is another pump in the system, usually at the engine but not always (remember old engine designs especially gas involved a mechanical cam driven fuel pump on the block), so it's a good design feature for them to fail in a flow thru mode such that the other pump can continue to supply fuel. An intank pump is usually all there is in the system so no reason to design it as a flow thru so that doesn't surprise me.

I suspect the humming you heard was the pump's internal electric motor "trying" to turn as the vacuum mechanically rotated its impeller. On a true flow thru pump, at least on the Facet, there is a check valve to prevent fuel reverse flow but flow in the forward direction is virtually unrestricted if the pump is not working.

Well said.
Now I need to decide whether to ditch the lift pump or figure out a relief valve setup to regulate the pressure to a much lower pressure before I break in the new CP3 pump in.

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

Jeepdan, after reading your post I guess I have the same decision to make,
I installed the pump out of a dodge 3500 hoping to avoid that issue.
Does anyone know if the pressure from that pump may be too great?

jeepdan · **Posted:** Tue Jan 03, 2012 11:00 pm

I read here that 4-6psi, is OK.
papainigo has suggested using a bleeder setup like blacklibertycrd had installed at the filter head. Relieving pressure by returning fuel back to tank. One could experiment with different orifice sizes. I wonder if the return line to the tank is large enough to handle the extra flow, so as not to effect the return circuit from the pump and injectors?

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

That's way above my pay grade.
pump arrived last evening. Doubt it will get installed today. Hopefully tomorrow.
I'll post the results.

jeepdan · **Posted:** Wed Jan 04, 2012 4:59 pm

mozzio wrote:

That's way above my pay grade.
pump arrived last evening. Doubt it will get installed today. Hopefully tomorrow.
I'll post the results.

What pump are you referring to, a different lift pump?
If you are talking about replacing the CP3 pump I would not attempt it without Miller Tool VM.1067. I learned that not only does the tool hold the gear pulley and timing belt in place, but more importantly it has a puller screw to remove the pulley without damage.
Use this
http://www.ebay.com/itm/MILLER-TOOL-VM- ... 730wt_952;
To avoid this:
http://s278.photobucket.com/albums/kk98 ... AG0280.jpg

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

I installed a lift pump(in tank) from a 3500 ram about two years ago and was worried about the pressure due to your posts
I am also installiing an injector(cp3?) pump.
Stopped by the shop today and the timing belt was going back on.
Couldn't believe it was 200 bucks for the belt. I didn't source it though.
Should be buttoned up in the am. We'll see if that fixed it or not.
There isn't much else to replace though.
Good luck with your install, it looked like a big job to me.

jeepdan · **Posted:** Wed Jan 04, 2012 5:26 pm

Keep us posted, What did you decide about the lift pump?

mozzio · **Joined:** Thu Jan 17, 2008 7:03 pm **Posts:** 59

Left it in for now. I thought it was only 5 psi when i was looking to install one.
It's been a while so I really don't know for sure.
When are you doing your injector pump?

dkenny · **Posted:** Wed Jan 04, 2012 5:57 pm

while I might take a different view on the max lift pump pressure..its just because it feeds a gear pump.. if the FSM is correct the output of the gear pump dumps excess pressure back to the tank at 73PSI..this includes air drawn in..
so I think feeding the CP3 with 15psi should not be a problem..using a vacuum is another problem..air in fuel..

change the timing belt without the miller tools..possible..been there done that..won't do it again..its a PIA!!
should I make the font larger..I didn't even remove or loosen the cam gears..

with i'm not following is why some think its the CP3..the only electrical part is the FCV/Mprop..everything is mechanical.
unless the CP3 is worn..and the tolerances get too loose a when its warm..not enough pressure during cranking and no start.
but codes while its hot? any or did I miss this information.

hey just my thoughts..
I've changed a CP3 in a Jeep.P0093 was the code..I think it was the FCV/Mprop valve not the CP3, but I cannot prove it.
I have the CP3..in pieces..care to make on offer?

-dkenny

Hot no start update

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