help I'm stumped
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Joined: Sep 2019
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help I'm stumped
Hello fellow bronco people.
Alright so I recently picked up an 88 5.0 from a buddy of mine. He got it after sitting 20 years or so in a garage. He got it going drove it 3 or 4 times around 60 miles round trip each no issue. Started acting funny (rough die-hard to start).
This is where I come in. It's my toy now.
Got it over to the house with a tow. Started messing with it and I cannot figure out why it will not start. Yes it has spark yes it has fuel yes it has air haha. I've pulled a plug and they smell like fuel crank it over and felt compression. Swapped cap a rotar I had a set. Found an article where they said their issue was a coolant temp sensor so I swapped that. I just dont get it.
It cranks and cranks. Acts like it's about to spark up and then nothing.
Any ideas?
Alright so I recently picked up an 88 5.0 from a buddy of mine. He got it after sitting 20 years or so in a garage. He got it going drove it 3 or 4 times around 60 miles round trip each no issue. Started acting funny (rough die-hard to start).
This is where I come in. It's my toy now.
Got it over to the house with a tow. Started messing with it and I cannot figure out why it will not start. Yes it has spark yes it has fuel yes it has air haha. I've pulled a plug and they smell like fuel crank it over and felt compression. Swapped cap a rotar I had a set. Found an article where they said their issue was a coolant temp sensor so I swapped that. I just dont get it.
It cranks and cranks. Acts like it's about to spark up and then nothing.
Any ideas?
Senior User
Joined: Aug 2013
Posts: 355
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From: Peoria IL
The 88 5.0 should have an OBD 1 computer. See if someone can read the codes & give you an idea where to start.
Any of those sensors could keep it from running -
If you have fuel, air & spark it will run - I'm betting the computer doesn't like something & is not popping the injectors.
Any of those sensors could keep it from running -
If you have fuel, air & spark it will run - I'm betting the computer doesn't like something & is not popping the injectors.
Mountain Pass
Joined: May 2018
Posts: 165
Likes: 2
This $29 OBD1 reader works great on my '94 Bronco.
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Mountain Pass
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Mountain Pass
Joined: May 2018
Posts: 165
Likes: 2
I remember on my 80's fords that the ignition module used to go out ALL the time and had similar symptoms.
Though when this happened, it would just turn and turn. I don't remember them trying to catch at any time.
There may be a way to test the ignition module, IDK. But Google is full of awesome guides for just about anything.
I'd start by replacing plugs, oils, plug wires, rotor, fuel, etc.
You'll want to do a full tuneup anyhow, once you get it running.
May as well do it now and eliminate a bunch of stuff as being a root cause.
Though when this happened, it would just turn and turn. I don't remember them trying to catch at any time.
There may be a way to test the ignition module, IDK. But Google is full of awesome guides for just about anything.
I'd start by replacing plugs, oils, plug wires, rotor, fuel, etc.
You'll want to do a full tuneup anyhow, once you get it running.
May as well do it now and eliminate a bunch of stuff as being a root cause.
Mountain Pass
Joined: May 2018
Posts: 165
Likes: 2
Oh and if the timing got knocked off, then that could cause these symptoms too.
Especially if it's trying to catch once in a while.
And verify your firing order vs how the plugs are.
I'm not 100%, but some (or all?) 302 & 351 have different firing orders so someone could easily get them mixed up. But in my experience, this would usually cause a rough idle, not a no-idle.
Unless maybe your plugs/wires/etc are in really bad shape.
Especially if it's trying to catch once in a while.
And verify your firing order vs how the plugs are.
I'm not 100%, but some (or all?) 302 & 351 have different firing orders so someone could easily get them mixed up. But in my experience, this would usually cause a rough idle, not a no-idle.
Unless maybe your plugs/wires/etc are in really bad shape.
Hotshot
Joined: Jun 2015
Posts: 12,872
Likes: 2,445
Not that one since it doesn’t have one of those.
As mentioned by others, check for fault codes and check fuel pressure with a gauge.
As mentioned by others, check for fault codes and check fuel pressure with a gauge.
Tuned
Joined: Aug 2002
Posts: 476
Likes: 1
From: Greatest state on earth
I agree that throwing parts at it is a bad idea. But when the plugs are wet, then not firing with compression. The ignition coil is one thing that has taken down all of my 86-96 I6/V6/V8 F150/Broncos at one time or another. Then ignition module and pip in distributor. Once running then sensors came in to play. I have an old school roll around diagnostic center like used all thru the late 70's-80's. It was free, but had all the updates for OBDI and some OBDII. Fun to play with and helping diagnose older efi aliments.
First thing first. Screw a pressure gauge to fuel rail and make sure it is within spec when cranking over. It should build up the correct pressure just by turning the key to run. You should be able to hear the fuel pump hum when key is in run position for the first few seconds.
One other thing to check out. On the 87/88 models, the wiring harness to fuel injectors is prone to corrosion. Double check all of the connectors and do a continuity check on every wire. Use dielectric grease on reassembly. Make sure grounds are good too.
First thing first. Screw a pressure gauge to fuel rail and make sure it is within spec when cranking over. It should build up the correct pressure just by turning the key to run. You should be able to hear the fuel pump hum when key is in run position for the first few seconds.
One other thing to check out. On the 87/88 models, the wiring harness to fuel injectors is prone to corrosion. Double check all of the connectors and do a continuity check on every wire. Use dielectric grease on reassembly. Make sure grounds are good too.
