Intermittent no start condition
 

I have an intermittent no start condition on my 98 Pontiac Stocker, 350 with Accell Calmap ECU. Randomly, the car will crank but not start. It might start 10 times in a row then the 11th. time ....crank, no start. Let it sit for a few minutes(5-10)...and it fires right up.
Recently, had a battery go bad....replaced it. The only other change was to the fuel. At Martin, had to switch to Sunoco as VP was not available.
Because it is intermittent, I have not been able to determine if this condition is fuel or ignition related. It has an MSD Digital 7.
Happened yesterday in the staging lanes at a test /tune.....waited about 5 minutes and it fired right up.

Anyone experience anything like this?

Thanks.

Re: Intermittent no start condition
 

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Re: Intermittent no start condition
 

Get a spark tester to verify that you have fire. If no fire, suspect optispark or ignition module on coil. If fire is present and it won't start, try pouring a little gas into the intake through the throttle body opening. If it starts when pouring gas (not the same gas that you recently changed to), it will be a fuel problem. It could possibly be bad injectors, or it could be fuel contamination. Just a few ideas.

Re: Intermittent no start condition
 

Thanks for the ideas. What fails on the optispark? I've seen references to this before as a problem area.

Thanks

Re: Intermittent no start condition
 

The optical sensor gets knocked out usually by a foreign substance. Oil, water. A quick continuity check of the harness should be done. Manipulate the wires as you do this. They can and do go bad as well.

Re: Intermittent no start condition
 

This thing has an MSD Distributor Cap,coil (HVC2) and crank trigger.

Re: Intermittent no start condition
 

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Re: Intermittent no start condition
 

Try a different coil---this typical of a MSD 8261 coil ---they cannot take a continous start and stop round after round like this without overheating and doing exactly what you are describing--- been there done that--- problem should be solved---FED387

Re: Intermittent no start condition
 

Started it tonight....fired right up. Ran for a minute.....shut off.....tried again 5 times over the next 3 hours....no start.
FED....would you recommend another P/N coil or get another 8261?

Also, I recall previously that the fuel regulator seemed to stay near operating pressure for quite some time after the pump/engine was shut down. This regulator (Paxton) is immediately bleeding off instantly after the pump is shut off (engine NOT running) Drops to 15 psi (set at 45) in about 3 minutes.
Wondering if this is the problem?

Re: Intermittent no start condition
 

try any other coil other than another a MSD 8261 if you are going to run more than a lap every hour or two just to see if that is the problem--- for repeat operation much like stock/super stock/ bracket cars go DO NOT USE the MSD 8261 it will usually do what you are describing---an MSD 8251 will not cause the symptoms you are describing---an MSD8261 coil gets so hot internally with repeat operation it breaks down due to the heat--- if you ran the car for a lap then shut it down for a while say 30 +minutes then ran another lap you MIGHT be OK but the MSD 8261 coil is not designed for lap after lap

Re: Intermittent no start condition
 

You mentioned fuel pressure....Does it give you 45psi when it cranks? Does it fall off? To bleed off that quickly upon shut off doesn't seem right to me. You also need to have 40psi minimum with the engine running to effectively fire the injector. Less than that and it can create problems. If we can get Ed Wright to chime in, he has a good deal of knowledge on these engines. Much more than me I suspect. One thing I failed to mention in my last post, is to check your grounds and wiring going to and from your crank trigger/ICM and coil, to include the weather connectors. If there is problems in either of these two circuits of wiring (bad ground or short while cranking), it can create a problem in having enough voltage to fire the engine off or a weak signal. I fought this condition for three weeks before stumbling across my problem.

Re: Intermittent no start condition
 

If you key on the DFI controller it should cycle the fuel pump for a couple of seconds then turn off until it cranks sees engine rpm above a certain rpm. If fuel pressure doesn't build up enough and you crank too soon, it might not build enough fuel pressure to run. I used an Accel conversion pressure regulator on my LT1. It used to hold full pressure for 30 mins or more after shutdown. You either have a leaking regulator or dirty fuel injectors that are leaking down. Also is your Opti-spark still hooked up ? There should be a connector in the Opti-spark that picks up the signal for timing the fueling. Depends on how your DFI is configured. Might want to check the connectors and wires. Does your Opti-spark have the ventilation system installed ? The later Opti-sparks had a vent system to prevent moisture from building up and corroding the components inside.

Re: Intermittent no start condition
 

Get a spark tester. It looks like a spark plug with a clip on the side (get the one that looks like a spark plug not the cheap plastic adjustable one if possible you will now what I mean when you see it). Unplug the coil wire and put the clip on your coil terminal and plug the coil wire on the spark tester like you would a spark plug wire. So that the spark tester is inline between the coil and the coil wire. While your at it get a noid light too. If you are not familiar with what a noid light is is plugs into the harness connector that plugs onto the injector. You can buy both of these tools at any auto parts store for probably twenty bucks or less. Then try to start the car until it does not want to start. You will know right away when you are trying to start it if it has spark because you will hear the spark tester snapping. If you have spark and it wont start quickly unhook a injector harness from a injector and plug in the noid light and crank it over. It should flash when cranking. This will allow you to figure out weather it is a injector pulse, spark or both problem. I dont have Accell system I use Holley, FAST and GM stuff on my cars. Does the Accell system use the OPTI for a crank signal or do you have a crank trigger?
Edit I just re read your posts so I know know it has a crank trigger. So See if one of the above is acting up (no injector pulse or no spark). Could be alot of things but we can figure out alot from knowing the results of the above tests. IE if its just no injector pulse or just no spark could be some things. IF it does not have spark and injector pulse it narrows it down some. Let me know what you come up with and I would be happy to try and help.

Re: Intermittent no start condition
 

Rob, I will get a spark tester and noid light tonight and run the tests. I'll post results.

Thanks for the tips. Testing these systems is a lot better than starting to throw money at parts.

Re: Intermittent no start condition
 

Steve and SS 3011
Sunday when the engine was running, the fuel pressure was rock steady at 45psi.

Also, the set up has a crank trigger and I have no knowledge as to the questions SS raised on the signal source and timing of signal.
I'm hoping the problem lies in the coil, regulator or perhaps crank trigger as these are relatively easy (but not cheap) fixes. The tests Rob suggested will provide some direction. If this is an ECU based issue.....that's a whole different scenario!!

Re: Intermittent no start condition
 

I may be wrong but I seem to recall the digital 7's having an LED on them that when blinking during cranking indicate it's seeing a trigger (crank sensor input), you may want to read the instruction manual on that. If it's in fact the case and you're seeing it blink, that would indicate to me that the triggering is working correctly. I'm not familiar with your system but most merely piggyback off the MSD for RPM (trigger) events which it needs to operate. Would be a quick way of determining what side to look at spark or fuel. Joe

Re: Intermittent no start condition
 

Thanks. I'll check out the MSD instructions.

Re: Intermittent no start condition
 

Yeah quick search looks like it does have the LED, hopefully it's in a position that you can see it. Without the crank input I'd imagine you will have neither spark or fuel activity. As SS3011 stated your set up MAY require a cam sync input to operate again not knowing your system it is merely a guess,any way of finding out how it's set up? Do you know who installed and set up the system, that would answer alot of questions. Again IMO I'd start by verifying the LED is blinking first.Good luck. Joe

Re: Intermittent no start condition
 

I ran my LT-1 with an Accel gen VII and a crank trigger.

I used an MSD 7al2 until it failed and than an MSD Digital 6

I did not send the crank trigger into the Accel ECU..

I ran it just like any std non efi engine. Timing was locked and set at the trigger.

I felt since I was new at this ....it was simpler and it was...

I gutted a stock distributer and added an MSD cap and rotor...

So my fuel pump and ignition were basically outside of the ECU...

The injectors of course have to run for the engine to start...

The tests Rob said to do should reveal the problem.....but you have to get it to NOT start first....

A cam sync sensor as I recall was only needed if your were running your EFI as a sequential firing order.....


P.S. I could not get my car to even start the first time I tried......wiring issue. ECU to MSD....

Re: Intermittent no start condition
 

Spoke with the previous owner/builder.
The Accell Calmap only controls the fuel map. The other functions(timing, rev limiters etc) are managed thru the MSD box. Rich, this appears to be similiar to your set-up.

I wiil get a spark tester and noid light tonight and perform the tests that Rob indicated.
Is there a universal noid light or do I need to buy the kit that has injector brand specific lights? I believe my injectors are Bosch.

Re: Intermittent no start condition
 

Ok, so basically the MSD is sending a tach signal to your EFI which it needs to indicate that in fact the engine is running. So you're still back to the basics, which can be indicated by a blinking LED, no blink, no start. I prefer the noid lights with a short pigtail on them so I can position it for easy viewing while cranking, if you have a helper this is a non issue. Look at your injector connector and get a light with similar terminals, as they've made a few different types over the years, there are some "universal" ones to chose from.Joe

Re: Intermittent no start condition
 

I have an MSD ignition tester and I just used it last Saturday.

It allows you to fire the ignition without running the engine.

It's a very handy item....but cost about $150 bucks I think

It can test the box, coil, chips and other items like a tach that is very often not accurate.......

Re: Intermittent no start condition
 

YEP everyone running an MSD should have one of these. Mine is out of the toolbox nearly every race.

Re: Intermittent no start condition
 

Here's the latest:
Tried to start car....no start
Checked rocker switch to make sure it was working...OK
Checked power to MSD box...OK
tried to start car...fired right up.....3 times....then returned to no start condition
LED working on MSD w/power on
Used spark tester to check coil output....OK
Disconnected crank trigger lead and , with ignition, shorted out green to purple wire which caused spark tester on coil to flash as the short was applied intermittently. This test was done per MSD direction. The only question I have here is that the spark was very weak from this test. Not sure of the correct level of intensity, but will call MSD again tomorrow.
None of the local auto parts stores had a noid light....Harbor Freight has a kit for $35, but I'll try to locate an individual tomorrow. The injector is a Bosch 80150756 with two flat blade terminals.

I hope to test the injectors tomorrow.
I appreciate all of your ideas and help. We WILL figure this out!!!

Re: Intermittent no start condition
 

Correction: injector P/N is 280150756....Bosch30#

Re: Intermittent no start condition
 

John,
Give me a call tomorrow later in the day. We had this at one time too. I will walk you through the tests. Call after 4. I have a charity golf outing.

Rich

Re: Intermittent no start condition
 

Will do.
Thanks

Re: Intermittent no start condition
 

Get a noid from any NAPA, or Snap On, Matco, etc.

Re: Intermittent no start condition
 

When the engine is in a no start condition...you need to just quickly see if the coil is firing as the engine cranks......

Get another coil wire with an old spark plug attached to one end......have it right under the hood ready to install on the coil and try to ground the plug on the engine.

Once it is in that no start condition install that wire with the spark plug on it into the coil and crank it.......if it has spark......quickly reinstall your normal coil wire and crank it....If spark was always there.....and it does not start.....and fuel pressure is good on your gauge.....45-50lbs......

Well it narrows it down to the ECU and fuel injectors.

There should be a tach signal from the MSD box to the ECU if I recall right. There is a single wire connection from the MSD to the ECU that has to be there and polarity correct.......That was the one I had trouble with.

Wire connections or a ground issue sound like what might be your problem......

I would go over all of that. The wiring diagram for the Accel ECU's was not hard to find and if I could recall the exact connections I would tell you but it's been a while....

It was all available at Accels DFI website.....

Re: Intermittent no start condition
 

Rich, I did test the coil immediately after experiencing the no-start condition. I placed the spark tester between the coil and the coil wire. Spark was there. I did not, however, test it on the other side of the coil wire (your process). I will do that tomorrow. That would eliminate or validate a bad coil wire. I will go through all the wiring this weekend....after I do the noid test.
I will find a noid between now and the weekend.
Thanks.

Re: Intermittent no start condition
 

Having spark coming out of the coil indicates you indeed do have the necc. trigger to initiate spark. Where you tested it isn't an issue, you've proven that the MSD portion is operational. I really doubt you would have a bad coil wire causing this as you would have other symptoms. Though it is a good idea to regularly change the coil wire as all the spark energy is directed thru it as opposed to single events thru the plug wires. Seems as though you are down to correct signaling to EFI controller or the controoler itself, BTW how are your injectors powered? The ECU merely provides the ground, if your power to the injectors is erratic you'll see the same issue. Joe

Re: Intermittent no start condition
 

Joe, I need to find out how the injectors are powered. There are enough wires under the dash that it will take some time to figure all this out. Also, crawling under the dash is an event in itself!
I talked to MSD again today...and I will do a resistance check on the crank trigger pick-up tomorrow. He said the reading should be between 65-85 Ohms. With this and a noid test, I should have enough info to determine the source of the problem....then finding the root cause may be another journey.

Re: Intermittent no start condition
 

John, having a spare crank sensor is a good idea regardless, however it seems apparent that it is not the cause of your problem, unless of course your no start "fixed" itself during your test. Do you know what switch you turn on to power the injectors? This would narrow the search a bit. As I've stated I'm not familiar with your system however can you "real time " communicate with it via a laptop and if so does it display any active parameters? Such as engine RPM? If so then you could monitor for RPM while attempting to start which I would expect to see, then during a no start event see if it is in fact displaying RPM. Hope this isn't too confusing. Joe

Re: Intermittent no start condition
 

Joe, Don't know which switch fires the injectors. I will assume it's either the ignition or fuel pump switch. Will be part of my "trace the wires" event tomorrow night and this weekend.
Relative to your other comments, I'm not familiar enough with the laptop interaction with the ECU to understand what you mean. This stuff is all new to me.

Re: Intermittent no start condition
 

Ok, can we assume that you have had the laptop connected at all? If so then you'll just have to look around and see what info is displayed, but I'd bet you'll be able to see engine rpm. That would help in determining whether the ECU "thinks" the engine is running. I would like for you to have comm. via laptop as soon as you can as it may help find the issue.Quickest way to find the power source I would think is to use a test light at the injector connector and start trying switches, the 1 that makes the lite come on is it, then it's a matter of tracing that 1 circuit. Once you get a bit more info you'll be fine, knowing how things are wired up is a huge step in the right direction.Please keep us updated on your progress and good luck. Joe

Re: Intermittent no start condition
 

Just freshened my engine. Now it won't start. No spark at the plugs. How do you check the pick up on the crank trigger with an ohm meter. Using a 7AL box and crank trigger. Carburetor set up. Just looking for some ideas. The coil is nearly new. The MSD parts are older but have been real reliable.

Re: Intermittent no start condition
 

There are 2 types of pickups. Magnetic and non magnetic.
Both have a coil of wire inside them and if you use an ohmmeter acorss that coil you should get a reading. I don't know what that reading is or should be for various pickups.....but an open reading would clearly be N/G
The wire is super fine and many turns.

MSD uses the flying magnet style and the magnets are in the wheel. The pickup is non magnetic.

With the ignition on.....you usually can get a spark out of the coil by connecting and than disconnecting the trigger wires that go to the MSD.

1 spark every time you break the connection.....

If you had an MSD tester you could test the box and the coil.

Pickups get blamed for a lot of ignition issues and routinely replaced but I really don't think they are usually the cause of most problems....

In the generator world that I work in .....similar pickups are used to generate a signal from the engine to a controller. We change them a lot when something is not working right but like I said I don't think they are ususally the problem unless they clearly have physical damage. If anything rubs the pickup face then it is likely to be damaged inside.

Re: Intermittent no start condition
 

I have been working on this stuff since it all started, Certified mech for 30 years. I went to a A/C Delco class many years ago and learned that the magnet type makes A/C voltage when cranking. I believe the spec is 3 volts. I can dig out my old books to confirm if needed. That will confirm signal strength which can cause intermittent problems.

Kirk

Re: Intermittent no start condition
 

Mike, make a small jumper wire, disconnect your crank trigger, with power on to MSD and a spark tester or an old spark plug on the coil wire (grounded of course) momentarily touch the jumper across the 2 terminals of the crank sensor harness. You should get a spark from the coil each time you remove the jumper.Other than that I believe you should see 800-900 ohms from the sensor, I agree with Rich crank sensors are very robust and do rarely fail though they're often blamed. I think MSD has a trouble shooting section on their web site but don't remember for sure.I'd bet someone you know has a MSD ignition tester, invaluable piece of equipment well worth the investment. BTW stay clear if the coils terminals as the have very high voltage potential DO NOT lay your arm against them (ask me how I know). Good luck. Joe

Re: Intermittent no start condition
 

KIrk yes they do produce an AC sine wave however the actual voltage can vary dependent on many factors, frequency and amplitude increase with engine speed.I've found that most (not all) have a hard time with the AC voltage test so a quick resistance test of the sensor or the jumper wire test usually indicates which way to procede. Thanks for sharing the info. Joe