Engine Another no start after washing engine bay

[bruno]

Hi All,

I sprayed the engine by on a lighter garden hose setting, like a rain setting. But looks like water got past something anyhow.

After drying the body down the car started and drove fine for a few miles. I stopped for an errand and when I got back in the car the engine wouldn't start.

I checked the dist cap, no visible water. Also, I still have the original rubber cover on it.

Tried starting it for an hour every 20 mins or so before I gave up and had the car towed.
This morning the car still won't start. I noticed some small water spots in the engine bay, so I'm going to let it dry for another day or two more before I start to worry. I've washed the engine bay this way for 30+ years with this car and this is first time that it won't start, usually it's just a miss fire that goes away in a couple hours.

Now reading posts I see some people saying to change the oil, as it may have fuel dilution. I'd never heard of this. I pulled the dipstick and it smells a little like fuel.

- Should I replace the oil before cranking it anymore?

Also, I pulled the plug on cylinder 5 and it's dry. No water, no fuel.

- What else should I check that could have moisture trapped to prevent start?

Hate to see the old girl on tow truck.



Thanks in advance.

 

[2000xp8]

Just start with the Cranks but no start checklist.
Regardless of how or why the engine won't start, the same rules should apply.
The only time i've personally seen water cause an issue is in the distributer, but as you suggested yours is covered.

 

[AeroCoupe]

Also, remember that when you depress the gas pedal to the floor the injectors do not fire when cranking. It is typically referred to as the “flood clear mode”. This will help to keep from pushing more gas into the oil.

Other thing is have you checked for ECU codes? The check engine light (CEL) only illuminates for emissions related codes so there can be codes present and no CEL.

 

[bruno]

Thank you for the replies. I'll go through the cranks but doesn't start list. And will check for codes.

Thoughts on the potential oil dilution; should I change the oil before solving the start issue?

 

[AeroCoupe]

Without being there to smell the oil I would say that call is yours. You seem concerned about it so I would just change it and put that one to rest in my mind.

 

[General karthief]

Yeah, I agree, change the oil, then grab some starting fluid and spritz a quick shot in the throttle body, you can cheat and shoot it through the nipple on the TB just pull that hose from the fill neck, if it starts or acts like it wants to start then its fuel delivery related. no start, no spark easypezy

 

[bruno]

Pulled codes last night.

KOEO 79 & 95
Continuous 34 & 95

Also, used the opportunity to buy a spark tester. I'm getting spark from the coil to the dizzy. But no spark from dizzy to plug.

I blew out the dizzy with air from compressor. No joy. Still no spark at plug. Pulled the spout, and tried again, no joy.

I'm still seeing some water spots from the wash in the engine bay. Maybe I use a heat gun, with a safe distance away, to warm up the area and help evaporation?

thoughts?

 

[gkomo]

Code 95 might be something to look at. Fuel pump secondary circuit failure.

Code 79 says it’s for AC/defrost on but during KOER not KOEO.

 

[nicholase]

In your fist post you mentioned cranking it many, many times over the course of an hour to try and start it. Then you pulled a plug and it had no fuel on it. That's a clue.

Check your fuel pressure when you turn your key on. Can you hear the fuel pump prime when you turn the key on? Also look into the code 95 like @gkomo said.

 

[85GTStangGuy]

Since you said "the car started and drove fine for a few miles. I stopped for an errand and when I got back in the car the engine wouldn't start.", it's possible it may have just been a coincidental part or circuit failure, unrelated to the actual engine bay cleaning. In other words, the issue may lie outside of the engine compartment.

 

[bruno]

An update.

Pump is not priming.

Checked the fuseable links on the wires off the starter solenoid, I'm no pro but they appear solid and ok.

I tested those wires for continuity and would only get a short beep. I'd remove the probes and touch them again and same thing short beep, no continuous tone. Is that typical of wires with fuseable links?

I then checked voltage at the fuel pump relay and inertia switch. The color of my wires are a little different than what Jrichker suggested in his old posts for tracing code 95. Here is what I found

Fuel pump relay:
Blk/pink is constant hot 12v
Orange/blue is switched 12v
Red is switched 12v
Tan/Green no voltage

Inertia switch:
Yellow/green is switched 6.8v
Black/purple no voltage

Im not sure which pins to jump on the relay to test if it's a bad relay. I've attached an image of the relay.

The inertia switch had no power unless key was turned. Then power only on one side and less than 12v, showing 6.4v.

I jumped the connection at the inertia switch and it made no difference, no pump prime.

- Should the inertia switch be showing less than 12 v? If not what could that mean?

I'm thinking it's the relay but would like to test it before buying one. Per the color wires in my photo which terminals do I need to jump to test if the pump primes when bypassing the relay?

Thoughts?

Thanks

 

[General karthief]

It's in the checklist

 

[bruno]

It's in the checklist

Oh, that bypasses the relay? I was wondering about jumping the relay terminals.

I tried the above and only got a click, pump did not prime.

 

[General karthief]

Pump dead?
I would rig power to jump the pump at the connection at the tank or the tank side of the inertia switch.

 

[AeroCoupe]

This thread is pretty good:

Engine Thread '1990 LX 5.0L EFI Mustang Fuel Management Problems - HELP!'

May 25, 2025

I bought this car with all the go-fast parts installed by a shop from the previous owner in Pennsylvania. When I bought it, it ran great with no idle or other misfire or rough idle issues. I moved back home to California and needed the car to pass smog certifications. I had to do the following to make it legal and register the car:

• Removed full-length headers & Shorty H-pipe
• Installed (used) 4-cat stock exhaust
• Installed shorty equal length CARB-legal headers
• Swapped out Edlebrock intake for a CARB-legal Trick-Flow Street Heat intake manifold

Aftermarket...

• 5.0LXStanger
• fuel delivery help needed lean pop rough idle
• Replies: 45
• Forum: Fox 5.0 Mustang Tech

 

[nicholase]

Oh, that bypasses the relay? I was wondering about jumping the relay terminals.

I tried the above and only got a click, pump did not prime.

It doesn't bypass the relay, it operates it.

The year of this would be helpful. There are several wiring versions. Some have the inertia switch located in different spots in the circuit. On some years it's in line with the pump and others its part of the relay control. They also use different wire colors.

I'd be cautious poking around jumpering things unless you are referencing a correct schematic. Accidentally sending power to a computer ground can be a bad day. Keep in mind the computer grounds the FP relay to activate it.

Myself and others can offer some suggestions, but need to know what year to give accurate info.

 

[Mindseye007]

Sounds to me like your TFI Module is done ,
check your current TFI Module, by buying this off Ebay https://ebay.us/m/ajc115
It comes with instructions on how to use.
And don't forget to buy a 9 Volt Battery.

get a new TFI module from Rockauto.

Motorcraft https://www.rockauto.com/en/moreinfo.php?pk=5434788&cc=1134010&pt=7172&jsn=17

 

[Mindseye007]

Hi All,

I sprayed the engine by on a lighter garden hose setting, like a rain setting. But looks like water got past something anyhow.

After drying the body down the car started and drove fine for a few miles. I stopped for an errand and when I got back in the car the engine wouldn't start.

I checked the dist cap, no visible water. Also, I still have the original rubber cover on it.

Tried starting it for an hour every 20 mins or so before I gave up and had the car towed.
This morning the car still won't start. I noticed some small water spots in the engine bay, so I'm going to let it dry for another day or two more before I start to worry. I've washed the engine bay this way for 30+ years with this car and this is first time that it won't start, usually it's just a miss fire that goes away in a couple hours.

Now reading posts I see some people saying to change the oil, as it may have fuel dilution. I'd never heard of this. I pulled the dipstick and it smells a little like fuel.

- Should I replace the oil before cranking it anymore?

Also, I pulled the plug on cylinder 5 and it's dry. No water, no fuel.

- What else should I check that could have moisture trapped to prevent start?

Hate to see the old girl on tow truck.



Thanks in advance.

Auto or manual transmission?

 

[AeroCoupe]

91-93 fuel pump wiring is in this diagram:

88-90 fuel pump wiring is in this diagram:

You need to check and see if the fuel pump relay has power from the battery (through the fusible link) and is getting power on the coil side of the relay from the ECU power relay. Once you have verified both of those then you ground the tan/light green wire (which energizes the coil of the relay) and see if the relay outputs power to the fuel pump. If you are getting power out of the relay to the pump then you will need to chase the wiring back to the pump so connector in driver side kick panel, back to the inertia switch, through the connector just above the fuel tank under the car, and through the fuel pump hanger connector.

What is weird is your relay appears to have the wiring colors of the 91-93 diagram but it looks to me that its under the seat co I am guessing this could be a late 91 or early 92 car?

One other thing, when you check for codes the fuel pump should do a prime sequence. If you do not hear it prime but you do not get a Code 95 then I would assume the pump has the bed.

 

[bruno]

Thanks all, it's a 1991, automatic. Fuel pump relay is under the driver's seat.

@AeroCoupe , thanks for the diagram, the 91-93 colors match my car. I'll get back to testing.