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1989 Bronco XLT 351W with C6, manual locking hubs. 6” suspension lift with 35” Cooper tires
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305 Posts
Discussion Starter #1
So ever since I’ve had this bronco, it seems to take forever to start the engine. When I turn the key, it turns over just fine but it keeps turning and turning then about 4-5sec later it hits and starts right up. When it starts though, it’s very slow. Like it’s struggling to actually start. Then it stumbles and cranks.

Now I’ve heard multiple “classic” vehicles act like this as well but MOST of them are carbed and not fuel injected. Now my father in law says “that’s just old trucks” but I fail to believe that. Is that ignition? Is that spark? Is that fuel injectors!?

Seeking some wisdom of the fine folks on here!! Thanks in advance!


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The Tennessee Warden
96 XL, 5.8L, E4OD, BW1356, 4.56 gears
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3,294 Posts
Is it a slow battery thing or a delay in starting after you turn the key? If it runs fine after starting, it sounds like you have a fuel starvation issue at startup. Can you hear the fuel pump prime when the key is turned on? Have you checked fuel pressure? If not, I’d start there.
 

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Registered
1989 Bronco XLT 351W with C6, manual locking hubs. 6” suspension lift with 35” Cooper tires
Joined
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305 Posts
Discussion Starter #3
Is it a slow battery thing or a delay in starting after you turn the key? If it runs fine after starting, it sounds like you have a fuel starvation issue at startup. Can you hear the fuel pump prime when the key is turned on? Have you checked fuel pressure? If not, I’d start there.
I can hear it prime when I turn the key. Fuel starvation is EXACTLY what I was thinking. What could that indicate? Also, I don’t have a fuel pressure gauge. After start up it’s fine but I have noticed lately it “bogging” down when I give it gas while cruising. It stutters then takes off. I’m changing the fuel filter soon. Where else can I check?


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The Tennessee Warden
96 XL, 5.8L, E4OD, BW1356, 4.56 gears
Joined
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3,294 Posts
I can hear it prime when I turn the key. Fuel starvation is EXACTLY what I was thinking. What could that indicate? Also, I don’t have a fuel pressure gauge. After start up it’s fine but I have noticed lately it “bogging” down when I give it gas while cruising. It stutters then takes off. I’m changing the fuel filter soon. Where else can I check?


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I would go to the parts store and rent a fuel pressure tester. It’s free as long as you bring it back lol. Pull off the vacuum line on the fuel pressure regulator and smell it to make sure it doesn’t smell like gas. If it does, replace it. Otherwise, your fuel pump(s) and filter may need a look.
 

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Registered
1989 Bronco XLT 351W with C6, manual locking hubs. 6” suspension lift with 35” Cooper tires
Joined
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305 Posts
Discussion Starter #5
I would go to the parts store and rent a fuel pressure tester. It’s free as long as you bring it back lol. Pull off the vacuum line on the fuel pressure regulator and smell it to make sure it doesn’t smell like gas. If it does, replace it. Otherwise, your fuel pump(s) and filter may need a look.
Awesome. Where does the fuel pressure tester hook up? Also, any idea of the parameters on start up?


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The Tennessee Warden
96 XL, 5.8L, E4OD, BW1356, 4.56 gears
Joined
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3,294 Posts
Awesome. Where does the fuel pressure tester hook up? Also, any idea of the parameters on start up?


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There’s a schrader valve on the fuel rail near the distributor - the pressure tester screws onto it. Keep a rag under and around it as you make the connections so fuel doesn’t get everywhere. Look for 35-45 psi when it primes and 30-45 when running. When you turn on the key, and it primes, wait a minute afterwards to make sure the pressure holds without leaking down.
 

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Super Moderator
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24,685 Posts
Yo Matt,
As MS88Bronc advised, Schrader Valve pic on driver side fuel rail;
159776
 

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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs.
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242 Posts
The fuel pressure regulator would cause the difference in pressure between primed and running btw. You can remove vaccum line on regulator and test with a vacuum pump if desired.
 

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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs.
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242 Posts
I've had leaky fuel injectors cause a slow start, but a power loss would agree with a fuel pump issue. Have you changed the filter?
 

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414 Posts
If fuel pressure is fine, then check timing. Should be 10 BTDC. Closer to TDC would make starting and idling struggle. Wouldn't be fun to drive either.
 

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82 XLT Lariat 351w, Edelbrock 1406 4bbl ,C6 auto, auto locking hubs ,33x10.5x15
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2,185 Posts
Just to go a different route... What kind of starter is on it? PMGR or...?
 

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Registered
1989 Bronco XLT 351W with C6, manual locking hubs. 6” suspension lift with 35” Cooper tires
Joined
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305 Posts
Discussion Starter #12
I've had leaky fuel injectors cause a slow start, but a power loss would agree with a fuel pump issue. Have you changed the filter?
I haven’t since I’ve owned it for about a year. Have one sitting in the garage so I’ll be doing it in the next few days.

The fuel pressure regulator would cause the difference in pressure between primed and running btw. You can remove vaccum line on regulator and test with a vacuum pump if desired.
How can you test it with a pump? I’ve got one so don’t mind trying.

Just to go a different route... What kind of starter is on it? PMGR or...?
I honestly have no clue. How can I tell?


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82 XLT Lariat 351w, Edelbrock 1406 4bbl ,C6 auto, auto locking hubs ,33x10.5x15
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2,185 Posts
Not exactly sure how to explain the difference but a PMGR has a unique sound, different from the factory starter...mine looks like this
mini-starter-2.jpg

Maybe someone can give you as better way to tell them apart. All I know is mine starts better and stronger with the PMGR starter and new 1/0 cables (battery to solenoid to starter and ground) and new battery clamps.
 
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