We have a 1993 Pace Arrow on the F53 chassis, with the 460 engine. About 60K miles on the clock.

It used to always start easily and run on the first crank, run perfectly, and idle smooth as silk. Just recently it decided not to cold-start so easily. I now have to crank the engine intermittently several times over a period of several minutes to get it to start when the engine is cold, such as after sitting overnight. When it does finally start, the "check engine" light comes on. It idles roughly, and black crud comes out the exhaust, and the "check engine" light stays on. It does this for about 8-10 minutes, until the engine apparently warms up. After the engine apparently warms up I hear a fairly loud distinct "click" from somewhere in the engine compartment, and simultaneously with the "click" sound the idle immediately smooths out and the "check engine" light goes off. This happens only when I cold-start the rig. It runs like a champ once I hear the "click" noise----simultaneous with the idle smoothing out, and the "check engine" light going off.

I have no problems at all once the engine is warmed up. Once it is warmed up I experience engine start-up and smooth as silk idle on the first crank.

I am not getting any EEC-IV codes.

Any theories out there?

 

This is just a theory, but something to look at possibly (you did ask for theories on this ) but the black smoke is usually a rich condition, and one of the most common problems for a rich condition on a FI engine is high fuel preasure so maybe you fuel preasure regulator is sticking until it warms up, so when it is cold turn it on without starting it, and check the fuel preasure, I believe it should be around 35psi. we just went through something similar in a 92 F350 check engine lite coming on black smoke idled really bad etc but his wouldn't quit and it ended up bieng the fuel preasure changed that out, and worked perfectly, in your case it could have just enough crude in the regulator to make it stick until it warms up some.

 

a 93 Pace Arrow huh? Well, you could afford to buy a 93 Pace Arrow...why not take it to a mechanic???I guarantee they'll fix it for you. I'm pretty certain that if you can afford the taxes and fuel for one, you can afford to pay a machanic the $45-$60 per hour to diagnose and fix it for you.
If it were carburated and not fuel injected, I would say the choke is messing up, but since it's injected, I would say probably the fuel pressure regulator also, but a professional mechanic could tell you for sure.

 

Hi 53wa2fl,

Your reply was less than helpful. I am not rolling in dough here. We live and work out of our motorhome. In any case I try to do as much of the work myself that I can. That's why I came to this forum for advice. I do not have the same faith as you in so-called "professional" mechanics. No way can you "guarantee" that a mechanic can do any better job than I can, given the proper tools and direction from those with the appropriate experience. I have had some work done by "professional" mechanics with outstanding results. But I have also had work done by so-called "professionals" and my vehicle came back more screwed up than before they touched it.

For the record, I installed a new fuel pressure regulator myself about 5K miles ago.

 

Hi monsterbaby,

Thank you for the helpful advice. I'll check the fuel pressure on my next day off. I change the fuel filter every 10K miles, and I installed a new fuel pressure regulator about 5K miles ago. The rubber diaphram on the OEM fuel pressure regulator gave up the ghost, and raw fuel was entering the FI system. Is it possible for a fuel pressure regulator to fail (or become stuck) after only 5K miles?

 

I used to be a proffessional mech, and have to agree they aren't always right, and diagnosing a problem over the internet can be difficult sometimes, the fuel preasure was just a place to start, and even though you replaced the reg it might not hurt to check it, ya just never know. Other than that can you maybe narrow down what exactly is clicking maybe start it, and lean over the engine till it does it to narrow that down some it might be relevant, and help us help you.
appearantly we were typing at the same time, so to answer you yes it is possible for them to go out in 5k miles have actually seen parts like that bad out of the box.

 

monsterbaby,

Thanks again for the help! Yes, it looks like we were typing at the same time.

I'll check the fuel pressure on my next day off. I'll also pull the vacuum line off the fuel pressure regulator to see if the rubber diaphram has ruptured or leaked. I had raw fuel bubbling up out of my OEM fuel pressure regulator, because the internal rubber diaphram had failed.

Tom Norman

 

[QUOTE=Tom Norman]
I have had some work done by "professional" mechanics with outstanding results. But I have also had work done by so-called "professionals" and my vehicle came back more screwed up than before they touched it.
QUOTE]
If you went BACK to the mechanic who messed your rig up even worse, then thats your fault. Now, I would suggest you go back to the mechanic who produced the "outstanding results" and have them take a look at it. Your right, I cant "guarantee" that a mechanic will fix it. Automotive mechanics are not all knowing. At best, they have a lot of knowledge, and can GUESS what is wrong with your rig. I appreciate that you arent "rolling" in money. Neither am I. It has been my experience that most mobile home owners are not capable of working on their own rigs. Of course, I speak from when I was working in a RV mechanic shop where we installed hydraulic leveling jack systems, headers, and did the occasional engine repair. This usually consisted of replacing a gasket or two. Todays mechanics have a lot less ability to diagnose problems than yetseryears mechanics did. This has to do with the computer systems of today. Usually, the computer systems are GREAT and work quite well....But when you have a problem like this, it's nice to have an old mechanic who has been around a while that can look at it. As Monsterbaby said, it is difficult to diagnose a problem over the internet.

 

Nope, I have never gone BACK to any mechanic who has messed up one of our vehicles. The problem is that we recently moved from Tennessee (where we had a shop and a mechanic whose work we consistently used and trusted) to South Carolina, where we have no contacts. The shop and the mechanic who produced consistently "outstanding results" is about 1,200 miles away from us. In short I'm on my own here until I can locate somebody I feel that I can trust. And I guess that I am in the minority of motorhome owners who has always done his own "routine" maintenance work. I can't justify paying anybody $40-$90 an hour to do an oil change for me or to change out air/fuel/breather filters. I have always tried my best to do as much as I can myself, using common sense, personal experience, and the experience of members of this forum. With any luck, I just might be able to fix this myself!

 

Another potential clue for consideration:

In the past, when I turned the ignition key to "on", the dashboard warning lights came on, and I could hear the fuel pump (inside the gas tank) hum very briefly before stopping. I then started the engine normally.

Now, however, if the engine sits for any length of time, when I turn the ignition key to "on", the dashboard warning lights come on, and I can hear the fuel pump hum for several minutes before stopping! This is all before I crank the engine to start it. Does this help in pinpointing the cause of my "check engine" light and cold-starting problems?

Tom Norman

 

i was thinking regulator the whole way through this thread, then i read that last post and that sounds like the regulator isnt telling the pump to shut off......im no FI mechanic but it sounds very pheasable.......

hey 53wa2fl, no offence but most people get on this forum so they dont have to go to a mechanic, ive been working on engines for 15+ years and know my way around 'em pretty good, but I still ask for opinions from the kind folks on here just to hear their input, and personally i dont trust anyone BUT myself to work on my rigs because i cant find an ASE certified mech. in this town that knows how to time a duraspark II ignition correctly, ive actually taught a few how to.....

BTW- (quote)"a 93 Pace Arrow huh? Well, you could afford to buy a 93 Pace Arrow...why not take it to a mechanic???I guarantee they'll fix it for you. I'm pretty certain that if you can afford the taxes and fuel for one, you can afford to pay a machanic the $45-$60 per hour to diagnose and fix it for you."

thats a crappy thing to say, heck, if i bought a 93 pace arrow i couldnt afford anything, let alone a mechanic.......

 

actually the regulator isn't what turns the pump on, nad off, that is controlled by a relay, and low oil preasure switch either of which could be bad although most likely is the low oil switch because usually when the relay goes out the pump doesn't come on at all. I personally don't think that is the cause of the current problem (although very well could be I guess just can't see how) but should probably be fixed anyway, as it is a safety item in that if your oil preasure drops too low it is supposed to shut the engine down before major damage can accure

 

1)I dont blame you for not trusting anyone else to work on your vehicle. I dont either
2)If you cant find an ASE cert mechanic in your town, I would suggest either a move, or going to the next town. And If you had to show some how to do their jobs, then thats something that needs to be addressed with their supervisors.
3)Have you ever heard of the saying "If you have to ask how much it costs, then you cant afford it"? Well, when it comes to a motor home, this saying holds a lot of water. Basicly, everything on a motorhome is expensive. Almost twice as expensive as a regular car or truck. If a person cant afford to maintain them, they shouldnt buy them is my point. You cant purchase a USED vehicle and expect it to be flawless. Now, this guy may have bought it new back in 1993, and to his credit, I can appreciate that he wants to do the work on his rig himself. But I think a decent analagy here would be as follows:
the TYPICAL RV'er working on their motorhome is like me trying to be a doctor. I'm not one....But I can fake it pretty good! I can prescribe a bandaid and a sling. I can even tell if you have a fever....but I have no idea where your spleen is in relation to your kidney. MOST motorhome owners know their motorhome has an engine, and they can point out where the alternator is on the engine, but they have no idea where the MAP sensor may be or what an EGR valve does. MOST of them know that they put in a LOT of gas/diesel, and it runs. Tom seems to be in the minority, and I apologize for grouping him into the majority of motorhome owners. MOST motorhome owners can afford to simply pay a mechanic to fix their motorhome, and they do so quite begrudgingly. It always irritates me when they gripe about having to spend a few more dolars that they CAN afford when the majority of other people cant afford to simply pay for something like that. That is all I'm getting at. I suppose I have a weird way of expressing myself, but thats ok. Some people may get upset with what I say on here...That is also ok. Their anger makes me happy. In short, everyone has an opinion....Thats because opinions are like bung holes..everyone has one and they all STINK! Mine included!
Tom, I truely apologize for grouping you in the majority or motorhome owners who for the most part couldnt tell a wristpin from a wristwatch. Have a GREAT day and I hope you figure out what is wrong with your rig. Hopefully, it is the least expensive thing possible.

 

Hey again,

1. I checked the pressure regulator and it seems OK. Not leaking fuel through the top like the defective OEM one did.

2. Here are the fuel pressure test results:

a)key on, engine off: About 30 pounds

b)key on, engine running: Pressure gauge wiggled between about 30-32 pounds

When I first started the engine the "check engine" light came on, it idled rough, and black crud came out the tailpipe. After a couple minutes the engine surged (increased idle speed), the "check engine" light went out, the idle smoothed out, and the pressure dropped about 2 pounds, back steady at about 30 pounds

c)key on, engine running, vacuum line at regulator disconnected and plugged: About 40 pounds

Each time that I reconnected the vacuum line to the pressure regulator the pressure dropped down to about 30 pounds. Each time I disconnected and plugged the vacuum line the pressure went up to about 40 pounds

The pressure went to about 40 pounds when I shut the engine off. It has maintained 40 pounds pressure for about twenty minutes with the key off.

After about twenty minutes elapsed, I turned the key to "on" again, but did not crank the engine. I again could hear the fuel pump running in the tank for a little over two minutes before shutting off. The pressure remained unchanged at about 40 pounds while the fuel pump continued to run. I then cranked the engine and it started normally, with no rough idle, and no "check engine" light. While running the pressure wiggled between 30-32 pounds.

3. Several folks have mentioned a fuel pump relay. Where is that little bugger located so I can check/replace it?

Hope these additional clues are helpful,
Tom

 

Sounds like the throttle butterflys are staying open or a no choke situation. Those are the typical symptoms anyway...

Edit:

I suppose the click could be the throttle doing something when it warms up. Do you touch the gas pedal at all when you try to start it cold?