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Fuel injected bug starting problem
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Marcas
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PostPosted: Fri Feb 17, 2017 12:44 pm    Post subject: Fuel injected bug starting problem Reply with quote

I have a 1978 convertible with standard fuel injection and everything else is more or less standard except for a svda distributor which I have been using with a pertronix ignitor for about the past ten years. The car runs well and performs exactly as it should, but has become hard to start when cold. The ignition timing is spot on, I have checked that the fuel filter is fine and have checked the fuel pressure with a gauge. The car starts fine when warm. I'm wondering is the pump taking some time to get up to pressure or is the pressure regulator leaking slightly, although there isn't much evidence of that from the readings. Any thoughts would be appreciated.
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PostPosted: Fri Feb 17, 2017 12:51 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

How's your cold start injector?
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PostPosted: Fri Feb 17, 2017 12:52 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

Marcas wrote:
I have a 1978 convertible with standard fuel injection and everything else is more or less standard except for a svda distributor which I have been using with a pertronix ignitor for about the past ten years. The car runs well and performs exactly as it should, but has become hard to start when cold. The ignition timing is spot on, I have checked that the fuel filter is fine and have checked the fuel pressure with a gauge. The car starts fine when warm. I'm wondering is the pump taking some time to get up to pressure or is the pressure regulator leaking slightly, although there isn't much evidence of that from the readings. Any thoughts would be appreciated.


When you say cold, how cold are you talking?

The FI system has an add-on system to assist in cold weather starting. This sub-system is completely separate from the ECU in that the ECU does not control it nor does it know/care that it exists.

The system consists of a 5th injector called the cold start valve which is located on the intake plenum. The CSV is controlled by a temperature-sensitive switch called the thermo-time switch.

The CSV is activated when BOTH of the following conditions occur:

1) The starter is operating
2) The temperature of the thermo-time switch is cold enough to activate it (I don't know the cutoff temp off the top of my head).

The termo-time switch gets power to an internal heating element when the ignition is turned on so after a while it will warm itself up past the cutoff temp so that repeated starting attempts don't flood the engine if the engine doesn't start right away.

Since you are only having issues starting when cold I might look at this subsystem first and make sure it's operating properly.
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PostPosted: Fri Feb 17, 2017 1:05 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

I suppose your hot air intake is intact, and its thermostat is working? It takes air from under the car. You probably know that but anyway...

Check the connections are tight on the double relay as well, and to the starter.
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PostPosted: Fri Feb 17, 2017 1:10 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

sjbartnik wrote:
Marcas wrote:
I have a 1978 convertible with standard fuel injection and everything else is more or less standard except for a svda distributor which I have been using with a pertronix ignitor for about the past ten years. The car runs well and performs exactly as it should, but has become hard to start when cold. The ignition timing is spot on, I have checked that the fuel filter is fine and have checked the fuel pressure with a gauge. The car starts fine when warm. I'm wondering is the pump taking some time to get up to pressure or is the pressure regulator leaking slightly, although there isn't much evidence of that from the readings. Any thoughts would be appreciated.


When you say cold, how cold are you talking?

The FI system has an add-on system to assist in cold weather starting. This sub-system is completely separate from the ECU in that the ECU does not control it nor does it know/care that it exists.

The system consists of a 5th injector called the cold start valve which is located on the intake plenum. The CSV is controlled by a temperature-sensitive switch called the thermo-time switch.

The CSV is activated when BOTH of the following conditions occur:

1) The starter is operating
2) The temperature of the thermo-time switch is cold enough to activate it (I don't know the cutoff temp off the top of my head).

The termo-time switch gets power to an internal heating element when the ignition is turned on so after a while it will warm itself up past the cutoff temp so that repeated starting attempts don't flood the engine if the engine doesn't start right away.

Since you are only having issues starting when cold I might look at this subsystem first and make sure it's operating properly.



And this is why I absolutely love this site. Precise, straightforward and knowledgeable information.

Best of luck OP.
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Marcas
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PostPosted: Fri Feb 17, 2017 2:44 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

Thanks for the replies. Sorry if I was unclear about what I meant by cold: I meant when the engine hadn't been started for a while. I don't think the air temperature is that significant. It is usually above 40 degrees F here at present, even in the morning. I have had the car for many years and the engine operates normally when it starts, with a fast initial idle before the revs drop to normal levels after the engine warms up.
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PostPosted: Fri Feb 17, 2017 5:50 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

Hi.
The complete testing of the cold start valve components would include the electrical test and the function test. The only difference between what I did at the dealer 25+ years ago and today would differ because of the availability of the rectangular cold start valve gasket.
So, today I would pull the connector off the CSV and use a standard 12v test light on both wire terminals. Disable the ignition to prevent accidental starting during this test. Crank the engine and you should see the test light on for approx. 6-8 sec's, I believe. If no light, then you need to determine if the test light is working and connected, or the issue is the 12v starter signal to the CSV and Thermo Time Switch, or the ground circuit wire (between CSV and TTS)or bad circuit within the Thermo Time Switch. Once you have the electrical repaired see if the car now starts. If not then you would remove the two screws for the CSV and with the valve out of the intake plenum, ignition disabled, crank the starter and verify that you see a conical shaped spray pattern for the 6-8 sec's. If no spray pattern verify fuel pressure. The cause may be a defective CSV.
Now, years ago the shops would see a couple of problems like the two wires reversed at the TTS or the wrong TTS.
Hope this helps, Bill.
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Marcas
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PostPosted: Sat Feb 18, 2017 1:13 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

Thanks for the suggestion. Will give that a try.
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PostPosted: Sat Feb 18, 2017 7:36 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

For some reason I have in my head ~50 degrees F as the temperature at when the CSV comes into play but that could just be faulty memory. Check Bentley manual for actual spec.
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Marcas
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PostPosted: Thu Feb 23, 2017 11:42 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

I finally got to check the cold start valve. Electrical check suggested proper operation as test light lit up for a time and then went out. Took the cold start valve out and it sprayed a concial spray when the engine was cranked. Thanks to Bill and others for the suggestions. If you have anything else I can try, will give it a go. If I'm using the car in the morning I often take it out of the garage, switch off and then drive it to work about ten minutes later. There is such a contrast between starting first thing in the morning and starting it 10 minutes later. On the second occasion the engine starts within a fraction of a second of the key being turned.
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PostPosted: Thu Feb 23, 2017 12:11 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

It would be nice to know if your aux air regulator ("AAR") is properly cleaned and adjusted.

http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=7834

We use spray carb cleaner, a hair dryer, and your kitchen freezer to adjust it.
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PostPosted: Thu Feb 23, 2017 1:36 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

It is certainly worth a look. I replaced a lot of parts about thirteen years ago as I thought it would be a good idea when they were still available and that was one of them. I think it is working properly as it ticks over at quite high revs for a few minutes and then settles down to just under 800 rpm.
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PostPosted: Thu Feb 23, 2017 1:42 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

It is certainly worth a look. I replaced a lot of parts about thirteen years ago as I thought it would be a good idea when they were still available and that was one of them. I think it is working properly as the car ticks over at quite high revs for a few minutes and then settles down to just under 800 rpm.
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PostPosted: Thu Feb 23, 2017 4:57 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

The quick tickover (that's "idle" to us yankees) then slow tickover a few minutes later sounds like your AAR is working. I would set the idle closer to 900-950 (warmed up) for better oil pressure and cooling at idle. This will only help the engine start and run cold. Try it and see how it does, then set it back if you don't like it.

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PostPosted: Fri Feb 24, 2017 1:16 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

Being in a different time zone from most of you, it is now morning here. Temperature is just below freezing outside. I turned the key out of curiosity as I didn't intend to use the bug today and it fired up immediately. I didn't see any evidence of poor electrical connections at the cold start valve, but that looks like it could be the answer. I probably won't need to use the car before tomorrow, so will check again then. In the meantime, thanks for all of the suggestions.
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PostPosted: Fri Feb 24, 2017 6:30 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

With my '78, fuel pressure is a big deal whan cold starting. If it's been a while since she's been started, I will pull the high voltage wire off of the coil, then crank the engine over for about 30 to 40 seconds to build up solid fuel pressure in the system, then reconnect the coil wire, then crank the engine and she starts up great. Probably a worn out fuel pressure regulator in my case- but once I do this procedure she'll start up perfectly all day.
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PostPosted: Fri Feb 24, 2017 9:01 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

Marcas wrote:
I finally got to check the cold start valve. Electrical check suggested proper operation as test light lit up for a time and then went out. Took the cold start valve out and it sprayed a concial spray when the engine was cranked. Thanks to Bill and others for the suggestions. If you have anything else I can try, will give it a go. If I'm using the car in the morning I often take it out of the garage, switch off and then drive it to work about ten minutes later. There is such a contrast between starting first thing in the morning and starting it 10 minutes later. On the second occasion the engine starts within a fraction of a second of the key being turned.


Hi. You stated the test light lit up for a time and then went out. Then you tried the CSV function test and it sprays nice. My question is how long was "for a bit"? As we discussed the CSV provides the ground for the CSV and it will vary due surrounding temp and the 12v starter signal. I believe I saw a graph sometime ago that plotted a curve based off of temp and time. At best the ground would be for 6-8 sec's. At its worst 0 sec's because of temp too high and/or heating element, within CSV, too warm.

As your warm engine starts fine is nice. It tells you a couple of things. One is the fuel pump circuit is holding residual fuel pressure, two battery is charged up so all electrical circuits work (ignition and fuel injection), and three engine is warm inside for easy combustion without any aids needed (choke or enrichment) and engine is within tune spec and mechanically sound.

Lets hope your engine continues to start up as you said it seems to be ok now.
Hope this helps, Bill.
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PostPosted: Fri Feb 24, 2017 10:19 am    Post subject: Re: Fuel injected bug starting problem Reply with quote

whobba wrote:
With my '78, fuel pressure is a big deal whan cold starting. If it's been a while since she's been started, I will pull the high voltage wire off of the coil, then crank the engine over for about 30 to 40 seconds to build up solid fuel pressure in the system, then reconnect the coil wire, then crank the engine and she starts up great. Probably a worn out fuel pressure regulator in my case- but once I do this procedure she'll start up perfectly all day.


Wow, that's quite an endeavor you perform to get the fuel loop pressurized. I would imagine on a type 1, or even any of the fuel injected models, it should only require approx. 10-15 sec's to fill and pressurize the loop. With a gauge one could see how long it takes to obtain the needed 30psi and if the regulator holds the required pressure. The filter should gravity flow and is easy to check. The fuel pump has specs that check its ability to pump an amount in a certain amount of sec's.
Why not have a temporary toggle switch, fused of course, mounted within easy reach, til you find a resolution for your dilemma?
Hope this helps, Bill.
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PostPosted: Fri Feb 24, 2017 1:05 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

You need the 900-950 rpm

Mine starts slowish and then goes to a fast idle at 900. At the moment is running perfect and no problem starting in minus 10, snow etc.

One problem I had was myself: I kept turning the key too aggressively too far, and discovered that I only needed a slight turn to start it every time.

Sounds like you just need to clean stuff (elec contacts and vacuum pipes) and reset the stock settings. An original DVDA distributor might help a bit. How is the S boot?
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PostPosted: Fri Feb 24, 2017 1:10 pm    Post subject: Re: Fuel injected bug starting problem Reply with quote

You should get fuel pressure immediately, all things being correct. You just tirn the key and no need to blip the pedal.
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