Intermittent Sputtering

[SShaw]

Recently, on occasion, my DeLorean will sputter a little when pulling out from a stop. I believe I let it warm up enough before driving. Sometimes it's fine when I start driving but then it sputters from a stop later in the drive. It's an automatic.

Confession - A few weeks ago I replaced the fuel boot cover and both fuel lines there. A couple of days ago it wouldn't start, the feed line came disconnected from the pump. After cleaning up, making sure the line to the pump was VERY secure and jumping the RPM relay to run the pump and check for leaks it started right up. A couple of starts later it cranked a bit before starting (air in the cold start valve?).

I don't know if that could be related. Could there still be air in the system somewhere? Go easy on me, I'm learning along the way.

[Jonathan]

Are you certain you got the replacement rubber hoses hooked up to the correct hardline?

Did you move, alter or adjust the pump itself when you did the work? Either the electrical connection on top or the orientation of the pump in the hole in the top of the tank?

[SShaw]

Are you certain you got the replacement rubber hoses hooked up to the correct hardline?

Did you move, alter or adjust the pump itself when you did the work? Either the electrical connection on top or the orientation of the pump in the hole in the top of the tank?

Yes, I'm certain I connected to the correct hard lines. I don't believe I moved anything. Maybe the boot rotated ever so slightly while tightening the clamp.

[Jonathan]

Got it. I believe you.

If you saw this sputtering happening before, do you think there is a good chance the problem isn't related to the fuel hoses (new or old)?

If that is the case, and your hose coming loose (same thing happened to me on the highway coming back from DCS, which I don't recommend in case you were wondering!) was just a coincidence, then maybe the problem is elsewhere.

You mentioned your car is an automatic. Was mentioning that just to add context, or is there something going on with the trans that makes you suspicious? How would you describe the sputtering (prior to the issue you had with the hose coming off)? Did you mean sputtering like it is about to run out of gas (and the same sounds you would hear if you ran your lawnmower or snowblower out of gas) or is the sputtering more related to a loss of power?

Any other gauges on the dash you've noticed have readings that might be a clue? Is your fuel sender working correctly? I assume the tank is at least fairly full while this is happening and not actually nearly empty?

[DavidProehl]

When replacing the fuel pump boot did you make sure that your pickup hose did not get kinked when fitting the boot? There is about a quarter turn that wants to happen when lowering the boot into the tank due to the molding of the pickup hose, you want to be sure you are letting the boot turn slightly otherwise that pickup line can kink.

Edit: Scratch that, just realized you said fuel boot cover, not fuel boot.

[SShaw]

Yes, I was very happy that the hose came off while parked. And, coincidentally, in the driveway and not the garage.

I mentioned it being an automatic for context. I don't suspect transmission issues. I noticed the sputtering before but it was only when I started driving and thought I wasn't let it warm up enough. So, I let it warm up longer. The hose coming loose may not be related.

It sputters a bit when pulling from a stop. It does seem to lose power, if I give it some gas it revs up and I'm good to go. I haven't checked the gauges when this happens. Though, my voltage is normally where it should be, the battery is fairly new and I recently replaced the alternator with a new 120 amp one.

I'm not sure about the fuel sender. It currently has about half a tank of gas.

[opethmike]

I know you mentioned you were careful, but I really do have to wonder about the fuel pickup hose. It may somehow have become twisted, or, if it is the original, it is becoming soft, and starting to collapse.

I had a sputtering issue similar to yours a few years ago, and inspecting that pickup hose, I found it to be collapsing.

[Jonathan]

A kinked or collapsing pick-up hose could be doing what you've described. It seems to fit but it could still be something else without seeing firsthand what happens and what else might be going on.

If you have already had the confidence to go in and replace those rubber hoses to the hardlines, going back in to lift up on the fuel pump and inspect below isn't that much more difficult. The orientation of the pump, i.e. where on the "clock face" it is pointing can lead to that hose getting pinched up against the inside of the tank. Or some other odd configuration. Warm weather and hot fuel can make matters worse when the hose starts to get too soft.

The revving of the engine to get it back again doesn't necessarily coincide with that theory, but I suppose it could. What came to mind with the auto trans and losing power was a dirty trans filter and loss of fluid, and then subsequent loss of power. Doesn't sound like that is it at the moment though, so I'd likely stick to investigating fuel stuff.

[SShaw]

Thanks, guys. I'll investigate the pickup hose. Maybe l rotated the boot more than I thought over the course of working on it.

[Ron]

$.02
Assuming you double checked the basics (timing, CO, etc):

Not to say that it couldn't, but I would expect a pickup hose problem to show up at higher RPM, where more fuel is used... I'd suggest putting a fuel pressure gauge on it and watching it while a helper puts it in drive and holds the brakes to load the engine a little, to simulating the condition. If that doesn't show anything useful, pull plug wires one at a time (while engine is still under load.) If you find any that doesn't change the RPM/sound, it is pointing to the culprit cylinder -- Suspect its injector, plug, vacuum leak...

[PJ Grady Inc.]

Keep in mind that a lot of different fuel or ignition problems could cause this symptom. It could be as simple as an intermittently arcing ignition wire etc.
Rob

[SShaw]

Keep in mind that a lot of different fuel or ignition problems could cause this symptom. It could be as simple as an intermittently arcing ignition wire etc.
Rob

There has been a lot of dew in the mornings recently which could maybe cause that? I don't know. Maybe I'll give it another week to try and isolate the circumstances before pulling out the fuel pump.

[David T]

If the sputtering (stumbling) goes away once it is fully warmed up, I would suspect a bad warm-up regulator. If it stumbles when hot it could be a lot of things.

[SShaw]

If the sputtering (stumbling) goes away once it is fully warmed up, I would suspect a bad warm-up regulator. If it stumbles when hot it could be a lot of things.

Yeah, it still stumbles on occasion when it's hot. Or at least I think it's hot after letting it warm up for a while and then driving for, say, 10min. But my temp never goes up much past the bottom of the gauge. I'll try replicating the issue some more to get more information.

In the mean time, this likely isn't related but maybe you can give me some input. It's hopefully easier to diagnose too. On occasion when I attempt to start the car the dash lights come on and that's it. No sounds at all. After a few tries it starts right up. This only happens when it hasn't been driven for a few days and only on the first start up. Once it starts I can turn it off and it'll start back up no problem. Starter going bad maybe?

[David T]

Yeah, it still stumbles on occasion when it's hot. I'll try replicating the issue some more to get more information.

In the mean time, this likely isn't related but maybe you can give me some input. It's hopefully easier to diagnose too. On occasion when I attempt to start the car the dash lights come on and that's it. No sounds at all. After a few tries it starts right up. This only happens when it hasn't been driven for a few days and only on the first start up. Once it starts I can turn it off and it'll start back up no problem. Starter going bad maybe?

If it stumbles when hot the first thing to check is vacuum leaks. Next would be the secondary ignition system (spark plugs wires, car, rotor, spark plugs). If it has been a long time since the last tune-up maybe you should do that. This other problem sounds like a starter problem. Do you hear the relays clicking? Is the car an early, low vin? Look up ST-05-2/82 and ST-32-12/81

[Ron]

In the mean time, this likely isn't related but maybe you can give me some input. It's hopefully easier to diagnose too. On occasion when I attempt to start the car the dash lights come on and that's it. No sounds at all. After a few tries it starts right up. This only happens when it hasn't been driven for a few days and only on the first start up. Once it starts I can turn it off and it'll start back up no problem. Starter going bad maybe?
Check and see if this starter relay wire modification has been preformed:
http://dmctalk.org/showthread.php?823-Starter-solenoid-circuit-modification&p=8412&viewfull=1#post8412

SEE: http://www.dmcnews.com/bulletins/ST-05-2.82.html

[SShaw]

If it stumbles when hot the first thing to check is vacuum leaks. Next would be the secondary ignition system (spark plugs wires, car, rotor, spark plugs). If it has been a long time since the last tune-up maybe you should do that. This other problem sounds like a starter problem. Do you hear the relays clicking? Is the car an early, low vin? Look up ST-05-2/82 and ST-32-12/81

I've had it for 3 months so I'm not positive when it's last tune up was.

VIN is 2412. No clicking when attempting to start. I'll look that stuff up now.

[Jonathan]

Double check the electrical connections on the ballast resistor as well as on the ignition coil. Post a picture or two of them if you want help confirming everything is where it should be. Tug on the leads to make sure they are tight. Visually inspect for signs of corrosion on or under the metal tabs.

[David T]

I've had it for 3 months so I'm not positive when it's last tune up was.

VIN is 2412. No clicking when attempting to start. I'll look that stuff up now.

The bulletin applies up to vin 2547 so this applies to you. If you don't know when the last tune-up was done you should probably do one. If you have over 30,000 miles you should also do an O2 sensor and a valve adjustment. Since you have an early car you should check that all of the safety recalls have been done too. Other things you should check, see if anyone put in a relay upgrade kit and is there anything plugged into the hot start relay?

[SShaw]

It doesn't appear the relay wire mod has been done but I'm not positive.

38608
38606
38607

[Ron]

The black wire is not factory...looks like a different mod.....Zilla?

[Bitsyncmaster]

It does not look like the starter relay mod has been done and that probably causes your occasional no start issue.

You have a LockZilla and FanZilla unit installed which replaced some of the stock components.

There is another modification to only turn the AC panel lights on when the cars lights are on which has not been done. Some have found the heat running those lights all the time can damage the AC panel.

Looks like your relays are original and lambda relay looks correct since it's the shorter relay.

Remove that fuse box cover. Leaving it on will make the fuses run hotter and may melt the fuse block.

[SShaw]

It does not look like the starter relay mod has been done and that probably causes your occasional no start issue.

You have a LockZilla and FanZilla unit installed which replaced some of the stock components.

It does look like some changes have been made to the starter relay. As mentioned above, the black wire may not be original. It also appears, if you look closely, a jumper wire has been cut which is part of the mod. I'll look again tonight. I took these pictures quickly last night.

A continued "thank you" for the help as I keep learning.

[Soundkillr]

Make sure the wur does not have vacuum on it once warm. If it does, it will cause random stumbling right at idle on take off.

[PJ Grady Inc.]

It doesn't appear the relay wire mod has been done but I'm not positive.

38608
38606
38607

The Fanzilla is laying on top of the CB's you need to look at. That's not ideal as they get hot enough to melt the housing if left like that. There should be enough room to move it off to the left of the breakers with a little clever juggling of the wires. My guess is you need to wire up the Start Inhibit relay as per bulletin and your ignition wires are going bad if the engine is moisture sensitive. The good news is you have those Zilla's which are highly prized and sought after IMHO!
Btw I just looked at the S.I. relay pic and the mod is not done. That is your intermittent no start issue. How about posting a pic of your Ignition wires next?
Rob

[SShaw]

The Fanzilla is laying on top of the CB's you need to look at. That's not ideal as they get hot enough to melt the housing if left like that. There should be enough room to move it off to the left of the breakers with a little clever juggling of the wires. My guess is you need to wire up the Start Inhibit relay as per bulletin and your ignition wires are going bad if the engine is moisture sensitive. The good news is you have those Zilla's which are highly prized and sought after IMHO!
Btw I just looked at the S.I. relay pic and the mod is not done. That is your intermittent no start issue. How about posting a pic of your Ignition wires next?
Rob

Thanks. I just put the Fanzilla there for the picture so you could see what I had. It's not normally there. I'll take a pic of ignition wires tonight.

[PJ Grady Inc.]

The black wire is not factory...looks like a different mod.....Zilla?

I just caught that too and it's my mistake that I didn't pay attention. The mod was done using that black wire instead of brown. I know because I just pulled the file on this car. It spans two PO's from'87 to '97 and we probably did the mod for the first owner. Back then I wasn't as anal as I am now and used a black instead of brown wire for the update. I'll never live this down! My guess would be that the starter solenoid contacts are the culprit here. The bakelite solenoid cap often overheats and causes a poor connection on the brass contacts. I'm sure Dave Swingle has seen that before right Dave?
Rob

[Ron]

...
Back then I wasn't as anal as I am now and used a black instead of brown wire for the update. I'll never live this down!
:angry_whip:


My guess would be that the starter solenoid contacts are the culprit here. The bakelite solenoid cap often overheats and causes a poor connection on the brass contacts. I'm sure Dave Swingle has seen that before right Dave?
Rob+1
I've see that hundreds of times (owned a rebuild shop).
Depending on the type, sometimes all the solenoid needs is the cap removed, the contact stud(s) rotated 180°, and flip the contact disk/bar.

It could be the contacts in the relay itself...
Or need the connection at the breaker cleaned up by now. (That's what had Jim F pulling hair for months although it 'looked good'.)

[Bitsyncmaster]

Or need the connection at the breaker cleaned up by now. (That's what had Jim F pulling hair for months although it 'looked good'.)

That reminds me of another fault. If that wire going to the breaker from the relay is plugged into the load side of the breaker, that sometimes will trip the breaker if you had left the fan on and you try to start it.

[Ron]

That reminds me of another fault. If that wire going to the breaker from the relay is plugged into the load side of the breaker, that sometimes will trip the breaker if you had left the fan on and you try to start it.I was going to mention that but assumed Rob was anal enough to make sure it was on the correct side back when. :deviltail:

...another thought- IF you do not any click at all, also suspect the ignition switch, starter itself, and neutral safety circuit (on an auto).

[PJ Grady Inc.]

:angry_whip:

+1
I've see that hundreds of times (owned a rebuild shop).
Depending on the type, sometimes all the solenoid needs is the cap removed, the contact stud(s) rotated 180°, and flip the contact disk/bar.

It could be the contacts in the relay itself...
Or need the connection at the breaker cleaned up by now. (That's what had Jim F pulling hair for months although it 'looked good'.)

Yes I've done that in a pinch. We have some NOS solenoids if it turns out to be the culprit. This is the most common failure point on the starter as it's fairly robust otherwise especially compared with the newer replacements.
Rob

[DMCMW Dave]

I just caught that too and it's my mistake that I didn't pay attention. The mod was done using that black wire instead of brown. I know because I just pulled the file on this car. It spans two PO's from'87 to '97 and we probably did the mod for the first owner. Back then I wasn't as anal as I am now and used a black instead of brown wire for the update. I'll never live this down! My guess would be that the starter solenoid contacts are the culprit here. The bakelite solenoid cap often overheats and causes a poor connection on the brass contacts. I'm sure Dave Swingle has seen that before right Dave?
Rob

I use the factory part for the mod (http://store.delorean.com/p-7224-starter-mod-wire.aspx) which does happen to be brown.

Agree - If you are lucky you can open up the starter solenoid and clean the contacts, but often the screws break off. On old Chevys you could flip the contactor and the terminal and it would be like new, but the DMC starter won't allow that.

In this case I agree he probably needs the recall.

[SShaw]

Thanks for looking up the records, Rob.

I think I may have found the issue. Is this part of the relay mod?

38656

[Bitsyncmaster]

Thanks for looking up the records, Rob.

I think I may have found the issue. Is this part of the relay mod?

38656

That looks like the diode from the otterstat. Better fix that wire so your cooling fans keep working when the engine gets hot.

[SShaw]

That looks like the diode from the otterstat. Better fix that wire so your cooling fans keep working when the engine gets hot.

Ahh, I fixed it up.

Thanks for all the advice on both issues. I have penty of leads to keep my busy for a while. I'll check back in if I have any updates!

[PJ Grady Inc.]

I use the factory part for the mod (http://store.delorean.com/p-7224-starter-mod-wire.aspx) which does happen to be brown.

Agree - If you are lucky you can open up the starter solenoid and clean the contacts, but often the screws break off. On old Chevys you could flip the contactor and the terminal and it would be like new, but the DMC starter won't allow that.

In this case I agree he probably needs the recall.

No you can flip the contact plate and terminals on the NOS "Paris Rhone" starter as I did it often when the cars were newer but solenoids were hard to source.

You are probably referring to the later service replacement "Valeo" starter which was gold in color. They were equally beefy but had a sealed non-serviceable solenoid.

The newer "High torque" starters currently available are about half the weight of the original at 8 & 1/2 lb's versus almost 16 lb's! Colin Chapman would approve especially since the savings comes off the abnormally heavy tail end of the car.
I do know from recent experience that the solenoid trigger post is easily damaged in shipping as it sticks out like a little outrigger (to use a nautical term). That is enough to put it the HT version out of commission.
Time will tell if the weight savings also means reduced service life but I suspect it may.

We offer both this starter and high quality rebuilt unit's for those who prefer one over the other.

Rob

[SShaw]

I'm back with an update.

The occasional no start issue seems to have resolved itself, at least for now. Maybe reseating the relay was all I needed.

As for the sputter off idle I checked 3 things. Fuel pump, vacuum leaks, fuel mixture (the PO told me he had to lean it out to pass emissions).

Fuel pump - Looked good from what I could tell.

Vacuum leaks - A small hose coming from the WUR was disconnected. I reconnected and haven't done a full check for leaks otherwise.

Fuel Mixture - My dwell meter was mostly reading 5 (10). On occasion it would give me a proper reading but not long enough to set the mixture. I realized that my frequency valve was only really buzzing when the dwell meter was giving a proper reading. The rest of the time the frequency valve only had a faint buzz and the dwell meter reads 5. It would appear I have an issue with my frequency valve?

[Bitsyncmaster]

Fuel Mixture - My dwell meter was mostly reading 5 (10). On occasion it would give me a proper reading but not long enough to set the mixture. I realized that my frequency valve was only really buzzing when the dwell meter was giving a proper reading. The rest of the time the frequency valve only had a faint buzz and the dwell meter reads 5. It would appear I have an issue with my frequency valve?

It's normal for the FV to have a louder buzz at 40 to 60 deg. than when driven to the min or max duty cycle. Same goes for the idle motor, when it's at 50% duty cycle it really will buzz loud.

[David T]

It's normal for the FV to have a louder buzz at 40 to 60 deg. than when driven to the min or max duty cycle. Same goes for the idle motor, when it's at 50% duty cycle it really will buzz loud.

Could also be a bad connection. Remove and replace the plug on the frequency valve a couple of times, that may do it.

[SShaw]

It's normal for the FV to have a louder buzz at 40 to 60 deg. than when driven to the min or max duty cycle. Same goes for the idle motor, when it's at 50% duty cycle it really will buzz loud.

I just leaned it out a little (counter clockwise) and at idle the FV buzzed consistently and the dwell held steady at 21 (42). Does that make sense? Could it have been so rich it was effecting the FV?

[Bitsyncmaster]

I just leaned it out a little (counter clockwise) and at idle the FV buzzed consistently and the dwell held steady at 21 (42). Does that make sense? Could it have been so rich it was effecting the FV?

Yes. When the engine has warmed up, the O2 sensor starts working (generating voltage) and that drives the lambda ECU to vary the dwell to the FV according to the mixture. With everything working, it takes less than a 1/4 turn of the mixture screw to drive the lambda ECU to it's minimum or maximum dwell (about 10 deg min, about 85 deg max). When your at those min/max points, the FV buzz is very little.

[PJ Grady Inc.]

There has been a lot of dew in the mornings recently which could maybe cause that? I don't know. Maybe I'll give it another week to try and isolate the circumstances before pulling out the fuel pump.

Yes the dew could be causing your wires to arc intermittently if they are due (No pun intended) for replacement. We have a file on two PO's of your car dating from 1987 to '97 and that's the year we last did a tuneup on the car. If it hasn't been done since this is likely your problem. Do not adjust the CO until all other engine issues have been addressed. If you send a pic I could probably determine if the wires came from us and therefore their age.
Rob