SORTIE

I am in the midst of a 1,000 mile vacation with my 1st gen and it's running fine.

on Saturday, we got caught in some horrendo traffic on 495 coming out of Massachusetts towards Maine. after about ten minutes of very slow going, both the "water in fuel" and "wait to start" indicators started to flash intermittently. nothing in the manual about that and engine temp, exhaust temp and oil pressure were all normal. five minutes after we got back to highway speed the indicators stopped flashing. it happened the next time we slowed down to a crawl as well, with the same result.

any thoughts?

SORTIE

at first I thought it was a bad ground, but why would the lights stop flashing after I was back to highway speed?

hasn't happened since, but I also haven't hit heavy traffic after running

dieselJon

I had that happen ONCE to me.

I was driving through a pouring rain and went through a low spot where a railroad used to go over the road. Down there, the water was close to 6" deep and I couldn't see it til too late. I hit it going 60-65mph and WHOOSH! Water hit. That is when the lights came on.

About 3 hrs later, and stopping to check a couple times to drain the fuel filter, it just randomly turned off. Another hour later came on for about 30 mins before turning off for good.

Maybe water got into a connection. Was it raining?

Crossy's son

Usually when those 2 blink it means the PCM is bad.....that's what my 91.5 did and I replaced the pcm with a used one now it's fine

hotwrench4hire

my 91 was doing that, shortly after the ignition switch shorted out

SORTIE

my ignition switch and assembly was replaced last August

didn't happen again for the rest of the trip, and most of my major driving pieces were in RAIN (although this happened on a perfectly dry day)

p.s. I can't remember what PCM is short for

ppiggppenn

PCM = Powertrain Control Module

SORTIE

what does a PCM cost if it needs replacing?

SORTIE

this continues to be a recurring issue.

it always happens after slowing down to a crawl after hard running

it can't be a short because it only occurs under certain circumstances

bannerd

I think the pcm from napa runs about 200$. Whens the last time you change your fuel filter? From the codes it sounds like a filter issue.

Water in fuel, wait to start. (Meaning, "I have water in my fuel, don't start me!")

I think if the PCM was bad you would be having more problems. Here is a list of what a PCM handles. If it was indeed bad expect failure in those area's

Water in fuel
Charge Air Tempature
Vehicle Speed Sensor
TPS
Overdrive (if equipped)
Crank Signal
Brake Switch
Speed Control
Ignition
Battery Voltage Readout
Wait to Start
Heater Grids

SORTIE

thanks for the response, I have done a boatload of work on this truck, including replacing the fuel lines and fuel pump (and draining the fuel tank completely), but I don't see a fuel filter listed on any of my repair orders! The "wait to start" and "water in fuel" indicators always go on in my truck once I turn the key to the grid heater position, but they both turn off prior to actual ignition. probably no harm in replacing the PCM too, especially if it's a simple operation.

what I don't get is the operation of these lights following stop-and-go traffic after highway speeds

SORTIE

it's not the "water in fuel" indicator, it's the "anti-lock brakes" indicator that illuminates in stop-and-go traffic after hard running

51 year old memory is crap

BigIron70

Most likely low vacumn to brake booster in go and stop traffic. May have leaking vac line or leaking brake booster.

bannerd

haha... yeah that could mean something different.

thrashingcows

Yup low vacuum would make the anti-lock brake flash. So check first to see how much vacuum the pump is generating. Then check your booster adn lines for leaks. The flashing "wait to start" is sometimes a bad air temp sensor. I know my truck has done that a few times...but mainly in the winter with colder temps.