No Start Just like last time.

Howdy Folks. Back to my No start problem I had before my stalling while driving problem. 93 4.9

Gonna run a bunch of sensor tests this afternoon, but my question is this.

Can a fuel pump be running and still produce low pressure? I always figured as long as it was on it would be working properly.

I don't have a fuel pressure gauge and my valve on my fuel rail is really hard to get to for some reason. I believe its under the intake manifold at the rear of the engine. is there a way to test it without buying a gauge?

p.s it was stumbling sometimes and fired/ backfired when I turned back the key from start to run also.

going to check map, icm, coolant sens, O2 , tps, iac,

disconnected battery after it drained from failing to start for 10+ min so comp should reset.

Tested CTS and MAP and may have found an issue already. ( battery is charged and not affecting results)

I was testing my MAP on the firewall and want to be sure I am interpreting my results right before I go out and buy one.

Voltage check with harness unplugged and key at the ON position testing VREF wire should be 4-6 volts, I got 5, so im in spec at the plug.

next step said to back probe the plug at the middle wire or the MAP B/P Signal connection with it plugged in. verified I had connection with back probe with ohms test before plugging it in to the sensor.

Engine Off, No vacuum, book says I should see 4-6 volts through sensor. and with vacuum it should drop to around 1 volt.

I got 2.5 volts with no vacuum, and no change when I tried the redneck vacuum test ( can't guarantee it was a valid test).

I want to be sure I did it right before I go spending money. even with the just no vacuum test that Indicated Failure.

Any one Agree the MAP Sensor is malfunctioning?

Yes it does sound like its bad with those readings, i would complete all of the tests before i replace anything. Good luck, let us know what else you find.

okay my tps came back good, I went ahead and swapped the MAP and it didn't fix my problem,

anyways now most commonly when turning over it will stop dead mid spin , my idiot lights and voltage gauge drop for a split second, then continues to spin again.

I am puzzled.

There are two kinds of MAP sensors, one kind you can test with a volt meter, the other requires a tach and dwell meter. The one on my '90 requires the dwell to check it. With that being said, I don't know if your MAP is bad. IF it was bad, it should throw a code. You would have cleared any code by disconnecting the battery.

Starter stops mid spin? Sounds like a dead spot on the starter, but I guess it could be a dead battery, or crappy connections.

Using a digital voltmeter, simply check across the battery terminals.

You should get 12.66 volts.

Next turn your headlights on for ten seconds and check again.

This dissapates any "surface charge"

It should still be in good shape.

Battery Charge Table

12.6V or higher: 100% charge

12.4V - 12.6V: 75-100%

12.2V - 12.4V: 50-75%

12.0V - 12.2V: 25-50%

11.7V - 12.0V: 0-25%

11.7V or less: 0% (and probably not capable of being recharged)

If it needs to be charged, charge it up overnight, and check it in the morning, as above.

IF it is dead in the morning you need to rule out if there is something draining the battery or if the battery just doesn't hold a charge anymore, and needs to be replaced. To test the battery, disconnect it, charge it up and let it sit overnight, then recheck the voltage. It should stay at the 12.66 overnight.

yeah i've got the battery on 2A charge overnight and will check in the morning, now back to the no start, its still stuck on firing occasionally but never enough to make it run, and trying to fire/ intake poping when you turn the key from start to run.

in relation to all my current and previous issues I have replaced to date: Coil, Distributor cap, Rotor, coil wire, Map sensor, and fuel filter. I have not changed my timing at all, and followed the original firing order on the cap.

I'm leaning towards icm as my culprit at this point, but it is the remote mounted one on the fender so the ones I have leftover from my 89 302 will not work.

some of the icm symptom articles I have found sound awfully familiar, no start, spontaneousness stalling ( from overheating ) then restarting a couple minutes later, when is doesn't stall completely it behaves like its got a rev limiter that keeps changing, shuddering at higher rpm cruising, and throttle hesitation. my truck has displayed all of these symptoms over the last 2 months.

okay so i did a ecm self test and at one point got either a 114 or a 14 which are ACT out of test limits or PIP circuit failure.

did a a voltage test for the pip in and I got my battery voltage which is what it should be.

then I did several A/C voltage out tests on the pip out wire by back probing the plug at the distributor.

book says 3 to 8.5 should be the reading. I got .5 to 1.5, followed the diagnosis and disconnected the ecm and re did test, same readings which means the ecm was not shorting the circuit, then unplugged the icm at the fender and got the same readings, just to be safe I re connected the ecm and left the icm and got the same readings. so my icm is not shorting the pip signal.

then did harness check for resistance and for shorting to ground and it came back good.

so that leads me to believe that my pip stator assembly is malfunctioning.

So while disassembling my distributor to change the pickup, my distributor gear shattered trying to remove it with a puller. found a gear from ford for 56 bucks, or a whole distributor from the bone yard for 45. anyways now if I have an issue with it in the future I have the 2nd partial distributor with the new pickup. havn't put in the new distributor yet so I still don't know for certain if my pip was my issue. I should know by the end of the day today.

wish me luck.

New Distributor is in and after adjusting the timing it runs like a champ.

First time i heard of pickup going on a Ford, Have seen it on GM'S in the past. Good troubleshootin!

budster 95 said:

First time i heard of pickup going on a Ford, Have seen it on GM'S in the past. Good troubleshootin!

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It's not as uncommon as you might think. They can short internally, usually when the engine gets warmed up but OK when cold.

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