Diesel RV Club, an FMCA Chapter

Ask Dave => Hey Dave, I've Got a Problem => Topic started by: willsonrick on February 27, 2019, 12:25:49 PM

Title: Hard Starting Cold
Post by: willsonrick on February 27, 2019, 12:25:49 PM
In my 98 Safari with a 3126B. If I let it sit for more than 3 days, it starts but, burps white smoke and idles rough for a few minutes. if I go to fast idle it will smooth out. Go back to idle it surges.

If I let it go for  a week or longer It take 30-40 seconds to start and belches a huge cloud of white smoke.
Also noted, it seems to have a lot more black soot on the exhaust and does blow a bit when accelerating.

I have followed the advice on this forum and others.

Did the bubble test at the fuel pressure regulator.  Replaced Racor 490 with the new 790 with electric prime. Replaced fuel line to the pump.

Thought I had it whipped.  No Joy. It starts ok after 1 or 2 days but, 3+ white smoke, runnuing ragged at slow speed again.
Replaced the fuel pressure regulator with CAT part.   No Help.

I am not in a place where I can run the bubble test again now. But,  It seems if all the fixes put in worked, that the system is slowly leaking by somewhere..

I am kind of at a loss as to where to go next. 

Real question is, can I get by working this way until I get home and have access to mechanic and shop or am I in real trouble?  It seems to work well when underway.

Rick Willson
Title: Re: Hard Starting Cold
Post by: Brett Wolfe on February 27, 2019, 02:08:45 PM

By pressure regulator, I assume you mean the one in the back of the head that the return line connects to. 

Don't know if you have the Caterpillar manual primer pump.  If you do, before trying to start next time, pump it.  If easy to pump, pressure has bled off.  If it is firm within a stroke or two no problem.

Have you verified that the INTAKE MANIFOLD HEATER is functioning.  There is a relay on  top of the engine that activates it.  When you turn the key to the first position, the intake manifold heater should come on.  When it does, voltage on the chassis battery and on the dash gauge should drop below 12 VDC, as that heater takes a lot of amps.  If not working, it makes starting a lot harder.
Title: Re: Hard Starting Cold
Post by: David.e.atherton on February 27, 2019, 04:51:39 PM
 Rick, your problem is startup of your engine and smoking is normal until engine get
to warm up to operation temperature. You are experiencing with your engine ECM is
still in the ( Cold Mode ), the engine will do real strange noises and exhaust smoke is
white in color. Damage by increasing engine rpm’s with cold oil under extreme high
pressure is asking for real problems. In most cases depending on how cold it is, the
engine operation will not straighten out and have real low power for about  15 to 35 minutes.
Your return fuel pressure regulator will  fall under different area you are trying to figure.
Last your engineTemperature Regular has been updated because problems with the
old style regulator keep engine in the cold mode.all the time and many missed diagnostic
troubleshooting the low power problem.  Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on February 28, 2019, 05:56:08 AM
I did replace the fuel Pressure regulator(sorry for the imprecise info).

The inlet air heater checks out also.   I might add that the temp here is 80 degrees.  I don't have the manual prime pump.

This has been ongoing since I overheated due to a water leak in the heater hose.  I pulled it over before shutdown but the engine did derate just before pulling over. 

I don't know about the cold mode issue.   It has been 80 degrees or above nearly every start. After starting the first time  in a day, I can shut it off immediately, and then restart and all is normal.  If I get to someone who has a CAT E reader will they be able to confirm one way or another? 

I have no expertise(except advice from fellow RV ers) to base this on , but, I suspect a leaking Fuel injector.  Having said that I , like Dave Atherton, would like to avoid spending money on parts until the real problem has been ID'd.

Thank for the advice and directions.

Rick Willson

Title: Re: Hard Starting Cold
Post by: David.e.atherton on February 28, 2019, 06:49:56 AM
Rick, ok what I’m getting from this last post . You had a over heating issues but can you go into
more detail, can you take me step by step from startup. Than driving down the road what goes
on until it runs ok or not than the next startup. This is very important and let’s not throw parts
at your problem with all this guessing. Any coolant loss, is the engine oil level raising, is there
Lot of blowby after start and running. What color is your smoke at different times running.
Do you have ny lights on dash or lights come on than off. Does engine jerk at climbing grades
is so what rpms. I can assist you but need all information from the start. Need your complete
Engine Serial Number first thing. Ask Dave, Dave Atherton Retired  Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on February 28, 2019, 12:11:03 PM
OK Dave  here goes

:Engine Serial  7AS15350            3126B

Let me start by saying I had a  1996 Safari with the same 3126B engine.  Aside from a few easly fixed problems it gave me no touble for 2 years.  Never really had to work on it.

That said this 1998 Safari is 5 feet shorter but weighs about the same. It has always seemed less strong than the 1996. Part due to the fact of gear ratios.  The 98 runs  about 1700 RPM at sixty vs 2050RPM for the 1996.

Back to the current issue.

The coach has about 90,000 miles and has run without flaw in the 3 years I've had it until this issue. Regular maintenance has been performed since I got it.

Coming back from the rally in OK the coach ran normally for the first 50 miles.  Water temps  indicated moving between 190 and under depending on hills. 

The temps started getting slightly higher and dropping down slower as we  kept going.   Finally after a few miles of this, the temps started easing up past 190.  I down shifted to 5 th to keep RPMs up on hills.  No help.  Said a couple curse words, started looking for a spot  to pull over.  Going uphill next time engine - derated.  Engine Light  Pulled over, Let idle for a couple of minutes. Ran out to the back and saw antifreeze all over the toad. Shut down engine.  Found leak in heater hose above exhaust manifold. Did not have proper repair parts or tools so wrapped a piece of instabond tape over the hole put baker on it and tie wrapped it.   

It took a little over an hour to get this accomplished. Proceeded to refill radiator very slowly. Put in 1 pint at a time.  Started engine before adding water.  Proceeded onward ,got coupler and hose clamps and replaced the field repair with a proper one.

Coach acted exactly like normal until next morning.  That's when the hard starting began.

Would not start until starter was run for about 30-40 seconds. White smoke coming out of exhaust the entire time. When it started to run on its own, it was really ragged sound and white diesel smelling smoke billowed for 10-15 second then disappeared when the engine smoothed out.

Next stop, same thing. same symptoms.

Next stop, same thing.
Made it home to SC.
Started to get advice about inlet air system from other forum and ended up at air leak into fuel system.
Called you and then did the Fuel pressure regulator hose test and  ID'd a leak. Traced that down to Racor filter.  Jumpered it out with coupler.  Ran it a few times like that and it seemed ok. It seemed ok if I started it every day. Let it sit for 4 days, went back to same problem.Replaced the Racor 490 with the new 790 with electric prime and the fuel line from the filter to the pump.

Came down to Florida.  Starting daily, no issues 3 or more days, hard start.

Replaced the Fuel pressure regulator. Used a CAT one. 

Same problem, can't sit for more than 3 days or problem reoccurs.

There appears to be no coolant loss after 1000mile.  No oil level Rise either.

White smoke only happens on the first start of the day. After that almost no smoke visible though the exhaust pipe seems to have more soot on it than I think normal. Black Smoke comes out if I floor it when almost warm, but not quite up to temp.

After the first start of the day, Driving there is no jerking, No alarms light or gauges are different than before.  No active are indicated.
Blow-by appears to be the same as before.

Using the diagnostic flash codes I got  39, 51,  15
Ijust got these I don't know when they are from but there are alrm or check engine lights.

That's the story, I hope you can help.

Thanks in advance.
Rick Willson

Title: Re: Hard Starting Cold
Post by: David.e.atherton on February 28, 2019, 03:45:36 PM
Richard, your flash codes if correct takes us to your problem.  Let’s start with flash code # 15,
Injection Actuation Pressure Sensor Erratic. Flash code # 39, Injection Actuation Pressure
System. Flash code # 51, Intermittent Battery Power to the ECM.

What I would like you to do, when engine has been sitting like when hard starting happens
and remove wire to the injection Actuation  Pressure Sensor ( location first sensor along
bottom of valve cover from front or fan side of engine above Heui pump.) this is a triangle
Shaped plug with 3 wires going to the IAP sensor. Note: engine cold do not try to start until
wire has been disconnected from sensor. What you looking for if engine will start and run,
If the engine starts than your problem is faulty IAP sensor. Let’s start here first and also very
possible dirty or shorted connection.  Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on March 01, 2019, 06:32:42 AM
Give me a 3-4 days to let it sit and I will get back on it.

Title: Re: Hard Starting Cold
Post by: willsonrick on March 05, 2019, 07:34:42 AM

Ok, Started rig after 5 days,  Disconnected the IAP sensor before starting.

Got white smoke and ran ragged for about 10 seconds before smoothing out. 

Let it run for a few minutes and it seemed to run normally. 

Redid the flash codes,   got a 39 and a 51 .  The 15 has disappeared.

I am ready for whats next. Thanks in advance for helping

Title: Re: Hard Starting Cold
Post by: David.e.atherton on March 06, 2019, 02:31:16 PM
Rick what you have just found your problem with the engine start with the injection Actuation
Pressure Sensor.  Sensor needs replacement ( off hand part number should be for replacement
Caterpillar number 161 - 1704 ). Yes engine, it ran rough at idle at first than ran smooth and
What all this tells you Sensor is bad, if Sensor was good there would be no engine start.
 The other flash codes will go away after new sensor is installed. Ask Dave, Dave Atherton
Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on March 07, 2019, 05:59:52 AM
Thanks Dave,

Glad you confirmed that. I was wondering about the rough start and then smoothing out.  I really appreciate you walking me through this.

Thanks again

Title: Re: Hard Starting Cold
Post by: willsonrick on March 26, 2019, 11:01:41 AM
Hi again Dave.
Made it home (900 miles) by starting coach every other day.  It ran fine.

I replaced the IAP sensor with a CAT part. The supplier said it was an updated version. (PN 224-4536) Started easily no rough
idle one day after shutdown. 

Started again today after 5 days.  Started right away, smooth idle, but a puff of white smoke.

I did the flash codes,  got a 15, 39 and 51 again.
I am ready for the next step.

Any help will be appreciated


Title: Re: Hard Starting Cold
Post by: David.e.atherton on March 26, 2019, 07:46:48 PM
Rick, think you need to have Cat ET connect into your system because you should not
be running. Do you have any attachments plugged into the data test port under the dash.
A sticky injection Actuation pressure regulator or bad connection. The little puff of smoke than cleared up is not a concern. Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on March 27, 2019, 06:52:47 AM

I was wondering about that.  Reading the Cat owners manual indicated I should not be running.  I can recheck all the connections.
Could corrosion in the ECM connections be the culprit here?  I don't have any attachments that I know of on the data test ports.  How do I know if I have a sticky IAP regulator.

I'd like to do all can before going to the CAT guys.  I appreciate all the help you have given me.  Is there any specific tests I should ask for when I find someone around here with a CAT E reader?

Thanks again.

Title: Re: Hard Starting Cold
Post by: David.e.atherton on March 27, 2019, 06:56:22 PM
Willsonrick, having hard time following you , you indicated before everything was fine now
same codes present which before you has 3 and one went away. Here is my question before
We can go further you indicated a puff of white smoke and same event code present that never went away before you installed the IAP sensor and everything working fine. Guess you maybe
need to fill me in is happening because what you are saying you should not be running along with lights on dash indicating a problem. I really need to know what is happening with engine
blow by blow or each puff . Kinda getting the following your problem is very minor.
Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on March 28, 2019, 09:21:17 AM

I think I mis-interpreted what the cat owners manual and what you said meant. I interpreted what you said as the engine should not run instead of,   I should not be running the engine. Here's exactly what happened this AM.

Turned key to on, all lights indicated normal start. The inlet heater came on and the check engine light came on like normal. Waited until the check engine light went out and held key in on Position for a few more seconds. The check engine light blinked once, than stayed off.  Started coach.  Very small puff of white smoke and engine stumbled once then ran smooth as silk.  The check engine light did not come back on and has never been on while running. My bad if I gave you that impression.  After starting I used the flash codes system to get 15, 39,51 codes.   I don't know if they are stored codes or new each time I start.

I haven't had time to check all the connections yet. Should get to it today. I hope this helps your troubleshooting. And I do hope the problem is minor.

Thanks again for your help


Title: Re: Hard Starting Cold
Post by: David.e.atherton on March 28, 2019, 09:12:58 PM
willsonrick, that sounds little better. One thing you do not understand when startup the
Heui engine has what is called a cold mode. Think I explained this earlier to you but the
engine will sound different idles rough , white smoke will be present Engine rpms will be
rough. Depending how cold outside can stay into the cold mode ( the cold mode is a ECM
safety Protection for your engine. Many people are in too big of hurry and start and full
speed ahead ( no engine warm up is where damage will happen to your engine.) let your
engine warm up and do not try to force cold engine oil through the injectors.. as far as the blink codes you listed you need Cat ET service tool to clear these event codes. Sounds like you
have your problem corrected. Last let your engine warm up at slow idle and do your walk
around safety check. Your engine will run out just fine driving down the road after about 1/2
hour gives youtime to do your walk around safety check.. Good luck and safe travels. Ask Dave, Dave Atherton Retired Cat amedhanic
Atherton Retired Cat Mechanic

Title: Re: Hard Starting Cold
Post by: willsonrick on March 29, 2019, 06:44:31 AM
Thanks Dave.

I really am glad to hear about the flash code clearing with the E reader.  My books don't address that.

Once again thanks for your help and patience throughout.

Rick Willson :)
Title: Re: Hard Starting Cold
Post by: David.e.atherton on March 29, 2019, 11:08:15 AM
willsonrick, back again and want to make you aware of removing data information. With logged
Information retained within your engine ECM and the engine hour meter and occurance count.
Retaining this information has a plus side ahead, for example same problems been going off
and on and many service shop later seems like problem is not corrected because there is
nothing to relate back to. Retaining data information now the technican can look back maybe
and find this problem been on going and now maybe something else is triggering the failure.
The part of a trained technican looking at problem as a police man looking at a crime scene.
The same signs keep appearing but cannot figure out what is going on.
Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on May 18, 2019, 09:01:26 AM
Hi again Dave,

I thought This problem was whipped, BUT.  I haven't really been using the coach much the last month or so.

I had the coach out the local CAT dealer to get the valves adjusted and the codes cleared. According to the tech no codes reappeared on the CAT E reader. 
I brought it home and it sat for a couple weeks.

Tried to start it and it went back to the same old problem.  First it fired right off, then died.  Then took about 45 seconds on the starter to fire and run.  It had a slight but noticeable surge for about a minute then ran smooth.   There was also white smoke. I let it run for a awhile and then shut down and restarted. Absolutely Normal. Started right away, no issues.  I did the flash codes again and got a 15.
At no time during all of this did the check engine light come on except at start.

I seem to recall that on my first Safari with the 3126  that I had a problem with starting  and I ended up replacing the IAP valve itself.

  It seems to me,  That it might be sticking somewhat when I leave it sit for a while.   Frequent operation it seems to be normal.   It would shock me to be right, but I figure you can steer me in the right direction.

Thanks in advance

Rick Willson, 3126B, 98 Safari
Title: Re: Hard Starting Cold
Post by: David.e.atherton on May 18, 2019, 08:21:18 PM
Willsonrick, what things sound like you have a air leak on the suction side of your fuel transfer pump causing your problem along with the smoke. Durning shut down with small air leak would
Break fuel suction, your fuel rail is charged with diesel fuel and engine will start than shut
down because your fuel transfer pump lost prime turning engine over fuel transfer pump again
would pickup fuel and start along with smoke which is caused from air in system.
Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Hard Starting Cold
Post by: willsonrick on May 19, 2019, 07:42:17 AM
Thanks Dave.  Are there any prime suspects to check?  I can inspect for obvious leaks but are there any internal points of failure like Check valves or similar?  Will some thing like this throw a code to a Cat e reader?

Thanks again

Rick Willson
Title: Re: Hard Starting Cold
Post by: David.e.atherton on May 19, 2019, 05:53:56 PM
Willsonrick, no a code reader would not pick up on your problem. First question, do you
have a Raycore water/fuel filter setup with the plastic site tube alongside side the water
Filter. If answer is yes this is the first area that would allow entry of air. This has been a
Low power caused air entry at this water/fuel filter. Next place, return fuel pressure regulator
which is located on back of engine head. Remove the fuel return line from regulator and
Put a piece of clear plastic hose from hardware store connect plastic hose to fitting on the
regulator and other end into a gallon container. Have someone start engine and see if air bubbles are present. Note: hold steady foot feed for two minutes at steady speed and do
not speed up and down. Than go to 1/2 of speed control and again hold steady. Than last
Go to 3/4 or high idle and again hold steady. Let me know the results.
Ask Dave, Dave Atherton Retired Cat Mechanic.
Title: Re: Hard Starting Cold
Post by: willsonrick on May 20, 2019, 05:08:13 PM
Got ya Dave.  Won't be for a few days. Messing with other stuff for the moment.  I have the Racor 790 system now.  When I replaced the old one I also got new fuel line from the filter to the pump.  I had run the bubble test before I replaced that filter. Makes sense to check again

Thanks,will let you know.


Rick Willson, 98 Safari, 3126B
Title: Re: Hard Starting Cold
Post by: willsonrick on June 08, 2019, 08:59:40 AM
Hey Dave, Back to home base so I could do the air test.   Started rig cold 3 days ago after 3 weeks without starting..   Started right up then died. Restarted and it ran extremely ragged and spewed white smoke. Steadied out after about 40 seconds.   It ran like it was surging a bit.  Not a big up and down surge but a mild barely noticeable surge.

Waited 3 days.   After rigging up for the air leak test at the pressure regulator, did a cold start.   It started right away, but I got about a 6 inch string of foamy fuel going thru the hose. That cleared up quickly and  we did the higher rpm and fast idle portion of the test.  Nothing, zero bubbles.  Coach ran smooth.   Shut down and restarted. No bubbles ran well. very slight surge, barely noticeable.

I suspect that you are going to tell me I have an air leak somewhere.  My plan, unless you tell me not to, going forward is to take down all the new parts I put in(  Primary filter assy, Outlet line from there to Fuel pump, IAP sensor, fuel pressure regulator) and re-install them with yellow teflon tape. 
  Thanks for any advice you can give

Rick Willson  98 Sahara 3006, 3126