Odd running (miss?)

Hi Larry,

the fuel lines should be pretty standard (8mm) ones.

But this one - tank to pump is 12mm.

Just a question, above you mention that they haven't been touched in 30 years although in your second post you had said:

I replaced the fuel lines about 3 years ago.

Not trying to be pedantic here :rolleyes: but it does make a bit of a difference, especially in relation to the initial problems that you were experiencing. If the fuel lines are old and disintegrating than this would be a very likely cause of the poor running. As the lines break down, bits of rubber break off internally and lodge themselves in the injectors (or clog up the filter, if in the lines before the filter).

I'd be replacing all the lines and filter in this case.

Cheers,
Dom.

Sorry Dom. I meant I did the injector hoses a few years ago.

That's a very good idea to replace the other hoses. We're enlightened in California and run 10% ethanol in our fuel which has the negative side effect of not being very friendly to rubber gas hoses. I'll be sorting through other hoses in the car during the winter. When I saw "winter" I mean rainy days when the car stays in the garage.

Larry
 
After you get the gas into a 10 gallon tote, what do you do with it? Do you siphon it back into the tank or into jerry cans?

Yes I transferred it into standard gas cans using a strainer.

The large bin was to deal with exactly what you had happen to you, a lot of gas spraying around.

Glad you got done with it and didn’t immolate the car, the house and garage or you...
 
Yes I transferred it into standard gas cans using a strainer.

Did you just heft it up or use a siphon? I figured I'd make more of a mess trying to carefully pour 50+ lbs of gasoline into anything and nixed the idea of dipping /filling a jug repeatedly since I didn't know I could get anything clean enough and wanted to limit my contact with the gas. I have a hand siphon at home, but after using it once to help a friend empty out a tub (long story), I swore I'd never use it again - we wound up going the shop vac route - but I didn't think that was a viable option for this.

The large bin was to deal with exactly what you had happen to you, a lot of gas spraying around.

There wasn't that much spraying gas... I put what collected in the oil drain pan into a gas can and it was less than 1/2 a gallon. Although it pumped out pretty impressively, not that much spilled on the ground.

Glad you got done with it and didn’t immolate the car, the house and garage or you...

As am I... but I did it in the driveway, away from anything that could add to the fun. Next time, I'll be sure to work from the side of the car.
 
Another update... I swapped in a replacement ECU and the problem didn't go away. I installed a new ground line to verify I had a good ground line and it seemed to get better... or so I thought.

Winter has finally hit us here in Northern California, so the past few days it's been an unbelievably cold 42F or so when I've been driving the car. It seemed to be running better but during a 15 mile drive (5 in town and 10 on the freeway) each way run this morning, the problem made itself known but only very, very slightly at about 3800 rpm in 4th gear on the freeway. When I say slightly, I mean it was almost imperceptible. The engine was well warmed up when the problem was happening

I'm assuming the next step is to replace the injectors - thus my post in another thread about finding FI line.

The fact the problem seems less bad when the outside temps are low is perplexing to me - I'm a photographer, but geek by past work experience. Is this "it's less bad when (baby) it's cold outside" leading me down the wrong path?

Larry
 
When it's cold the air is more dense. If the issue you have is with a leaky injector (spilling too much fuel) then during "normal" temps you might be running rich...but when the ambient temps are lower and the air is more dense, then the AF ratio changes (leans out due to greater mass of O2) enough to make the "miss" seem like less...

SteveC
 
When it's cold the air is more dense. If the issue you have is with a leaky injector (spilling too much fuel) then during "normal" temps you might be running rich...but when the ambient temps are lower and the air is more dense, then the AF ratio changes (leans out due to greater mass of O2) enough to make the "miss" seem like less...

SteveC
Thanks for the explanation Steve.

Larry
 
I had an odd miss situation with my car early last year. It would cut out intermittently above about 3500 rpm but only on heavy acceleration, and only when "warm," meaning after a cold start when temps had gotten up to 150-175; when it got to full operating temperature, no cutout. Check the usual stuff like you did, AFM swap, checked fuel pressures, replaced fuel filter, checked cap/wires/rotor.

I replaced the coil and that solved the problem. It took a while to find what I thought was a good quality coil---a Bosch red coil 0 221 119 030, but one made in Germany, not newer stock made in Spain, Brazil, or "elsewhere."
 
About time for an update. I've been working on the car here and there and now that Spring has Sprung, I'm back with another problem, which developed a month or so ago. The original problem is still there, but I can live with it for now. This problem is a bit more pressing but equally perplexing.

The car has an '84 FI engine that was transplanted into it about 20-22 years ago. The car has 335,000 miles on it, the '84 engine/transmission about 150,000 miles.

The car starts fine when it's been sitting for long enough. However, after I get it up to operating temperature and then shut it down and sit for 30 minutes or more, it acts like it's flooded. It'll crank and sound like it's about to start, but won't. I can also get it well-warmed up in my garage, then shut it down, leave it parked with the engine cover closed for say an hour to let it heatsoak, come back and it won't start - it cranks, sounds like it's about to a few times, but doesn't.

So far, I've replaced:
Ignition Amplifier (with one of the rebuilt ones Jeff N was selling in 2015)
AFM
Water temperature sensor
Coil
Ballast Resistor
Wire that runs between the Ballast Resistor and the positive side of the coil.
Subharness that goes between the Ballast Resistor, coil and Distributor
Fuel Injectors + lines + injector holders + o-ring seals
Cold Start Valve
Fuel Filter
Ignition Brain in the spare tire well
Distributor
Distributor Cap
Distributor Rotor
Spark plug wires
Spark plugs

I've also run a test lead from the battery to the non-coil side of the Ballast Resistor to see if that would help get the car to start but that also didn't make a difference.

The timing is correctly set - 10 degrees BTDC (I followed the wiki).

Looking for suggestions on what to do. I can now only sit in my car and make 'vroom vroom' noises... which while fun, isn't really that much fun...

Larry
'79 X1/9
 
I am wondering if the fuel rail loses pressure while standing, and that you get vapor in the lines. One ting to try after a good heat soak: Remove the rubber elbow between the air filter and the AFM. Turn on the ignition and poke your finger into the AFM to open that flap / trap door, which should turn on the fuel pump. Listen for the sound as fuel is being pumped through the system. Does it settle down to a steady sound of fuel flowing rather quickly, or is there a lot of gargling / hissing sounds? After you get a steady sound of fuel flowing, try starting the car.

If fuel pressure bleed off is the problem, the first place I would look is the fuel pressure regulator. You said the fuel injectors are new, so they are probably fine. There is a check valve in the fuel pump. It is there to maintain fuel pressure when the pump is not running. I don't know if these are prone to leaking.
 
I am wondering if the fuel rail loses pressure while standing, and that you get vapor in the lines. One ting to try after a good heat soak: Remove the rubber elbow between the air filter and the AFM. Turn on the ignition and poke your finger into the AFM to open that flap / trap door, which should turn on the fuel pump. Listen for the sound as fuel is being pumped through the system. Does it settle down to a steady sound of fuel flowing rather quickly, or is there a lot of gargling / hissing sounds? After you get a steady sound of fuel flowing, try starting the car.

If fuel pressure bleed off is the problem, the first place I would look is the fuel pressure regulator. You said the fuel injectors are new, so they are probably fine. There is a check valve in the fuel pump. It is there to maintain fuel pressure when the pump is not running. I don't know if these are prone to leaking.

I'll give that a try tomorrow and will post the results..
 
As Bjorn mentioned, the cause of hard hot starting on an FI car is usually vapor-lock related. If the fuel system loses pressure due to fuel boiling, it's normally due to things you can't see with the naked eye: leaking injectors, a bad fuel pressure regulator, or a bad fuel pump check valve.

Funny thing is that the two items (fuel pump and fuel press regulator) that Bjorn mentioned are the only two FI items that you have not replaced.

I'm guessing that the engine transplant did not include transplanting the FI injector blower system?
 
The other reason a FI car will fail to start when warm is that it can flood, the culprit is generally the cold start circuit. As you have replaced the Cold Start Injector already (so presumably it is not leaking) then I would look at the Thermo Time Switch for proper operation.

The next time this happens, try removing the electrical connector from the cold start valve and try starting the engine. You may need to hold the gas pedal to the floor for a few turns to clear some of the excess fuel in the manifold to get to an ignitable mixture. If removing the electrical connector fixes the problem, I would look at the TTS to start.

To test the TTS, the engine must be completely cold to conduct this test. I would perform this test when the air temperature is less than 70 degrees. Disconnect connector from cold start valve. Install a 12v test light or voltmeter to the connector. Operate the starter and note that the thermo time switch should provide power for 1 to 8 seconds while the engine is colder than 95 degrees F. Above 95 degrees the sensor should not provide power at the cold start connector. If it does, it is either not in the right place to receive the heat it needs to work properly or it is defective.

If the hot start issue still persists, try collapsing the fuel supply hose to the cold start injector or better yet remove the cold start injector to see if it is a leaking. If leaking replace.

If this doesn’t solve the problem I would check your coolant temperature sensor (the FI one not the one for the gauge). From Brad Artigue’s guide it should be checked at the FI ECU connector to verify that the sensor and the wiring from the sensor to the ECU is correct. This image is from Brad’s excellent fuel injection guide:

FC007442-022E-440D-BAF6-FDECEF85473D.jpeg


If the sensor is not providing the correct reading for the temp, the ECU could be enriching the mixture by adjusting the cycle time of the injectors also leading to a too rich or flooded condition.

Hope that helps.
 
As Bjorn mentioned, the cause of hard hot starting on an FI car is usually vapor-lock related. If the fuel system loses pressure due to fuel boiling, it's normally due to things you can't see with the naked eye: leaking injectors, a bad fuel pressure regulator, or a bad fuel pump check valve.

Funny thing is that the two items (fuel pump and fuel press regulator) that Bjorn mentioned are the only two FI items that you have not replaced.

I'm guessing that the engine transplant did not include transplanting the FI injector blower system?

It did, but the bits came in a box.

But I've owned the car for 19 years and have never experienced this problem before. The only time I've ever had a problem with vapor lock or acting like it is now was when the ambient temperature was 109 F (fortunately, about 4 hours north of here) and I'd shut the car down for a 3-minute rest stop. So I have to ask, why would this problem suddenly come up?
 
The other reason a FI car will fail to start when warm is that it can flood, the culprit is generally the cold start circuit. As you have replaced the Cold Start Injector already (so presumably it is not leaking) then I would look at the Thermo Time Switch for proper operation.

The next time this happens, try removing the electrical connector from the cold start valve and try starting the engine. You may need to hold the gas pedal to the floor for a few turns to clear some of the excess fuel in the manifold to get to an ignitable mixture. If removing the electrical connector fixes the problem, I would look at the TTS to start.

To test the TTS, the engine must be completely cold to conduct this test. I would perform this test when the air temperature is less than 70 degrees. Disconnect connector from cold start valve. Install a 12v test light or voltmeter to the connector. Operate the starter and note that the thermo time switch should provide power for 1 to 8 seconds while the engine is colder than 95 degrees F. Above 95 degrees the sensor should not provide power at the cold start connector. If it does, it is either not in the right place to receive the heat it needs to work properly or it is defective.

If the hot start issue still persists, try collapsing the fuel supply hose to the cold start injector or better yet remove the cold start injector to see if it is a leaking. If leaking replace.

If this doesn’t solve the problem I would check your coolant temperature sensor (the FI one not the one for the gauge). From Brad Artigue’s guide it should be checked at the FI ECU connector to verify that the sensor and the wiring from the sensor to the ECU is correct. This image is from Brad’s excellent fuel injection guide:

View attachment 21948

If the sensor is not providing the correct reading for the temp, the ECU could be enriching the mixture by adjusting the cycle time of the injectors also leading to a too rich or flooded condition.

Hope that helps.

Thanks Karl...

... silly question for those that know what an Ohm meter is but haven't really used one for years...

Since we're looking for the resistance from, after unplugging the ECU and connecting the Ohm meter, I'm assuming the key does not get turned on (or even has to be in the ignition switch)?
 
Thanks Karl...

... silly question for those that know what an Ohm meter is but haven't really used one for years...

Since we're looking for the resistance from, after unplugging the ECU and connecting the Ohm meter, I'm assuming the key does not get turned on (or even has to be in the ignition switch)?

No power involved. The ohm meter measures the resistance in ohms through the two connections and the component (the sensor). The key must be off (and remove the negative lead from the battery just to be sure) before removing the connector from the ECU.

Then looking at the harness ECU connector with the wires leading to it with the wires to your left, you are going from pin 5 to pin 13 to measure the resistance. Sorry I should have stated that previously.

If the test fails at the connector also do the same test at the sensor itself to ensure that the wires are not the culprit.

Brads document can be found here: https://www.mirafiori.com/faq/fiatFI_may2002.pdf

I would also download the fuel injection trouble shooting document which can be found on the Xweb Wiki.

(Made a couple of edits to clarify)
 
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It did, but the bits came in a box.

But I've owned the car for 19 years and have never experienced this problem before. The only time I've ever had a problem with vapor lock or acting like it is now was when the ambient temperature was 109 F (fortunately, about 4 hours north of here) and I'd shut the car down for a 3-minute rest stop. So I have to ask, why would this problem suddenly come up?

Probably due to age failure of the fuel pressure regulator and/or the fuel pump check valve. Or as Karl noted, failure of the cold start system.
 

No power involved. The ohm meter measures the resistance in ohms between the two connections. The key must be off (and remove the negative lead from the battery just to be sure) before removing the connector from the ECU.

Then looking at the harness ECU connector with the wires leading to it with the wires to your left, you are going from pin 5 to pin 13 to measure the resistance. Sorry I should have stated that previously.

If the test fails at the connector also do the same test at the sensor itself to ensure that the wires are not the culprit.

Brads document can be found here: https://www.mirafiori.com/faq/fiatFI_may2002.pdf

I would also download the fuel injection trouble shooting document which can be found on the Xweb Wiki.

Thanks. I appreciate the detailed explanation.

I've pored over Brad's document - it's very nicely laid out. I hope to fiddle with the car on Sunday...
 
If the Fuel Pressure Regulator diaphram is bad it will allow fuel to leak and/or sucked out of the FPR into the plenum, resulting in a flooded condition. Pull the vacuum hose off the FPR & smell (not the larger return line). If it's leaking, you will smell fuel. Note that if this is the case, you need to also change the oil ASAP as the excess fuel will absolutley contaminate the crankcase & therefore the oil. This is a pretty common failure symptom on '80's Volvos utilizing the same design FPR.

If you can check fuel pressure, you may or may not see a rise/drop due to the bad diaphragm, but it will always be evident by smelling the vacuum line
 
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