woogasnerk

I just got a 1990 F150 and it's my first Ford. I'm trying to get it to start and run long enough to run a code reader. I bought it from a guy who took it as payment for a job, and he tinkered with it a bit before he sold it. He said the ignition module on the distributor was missing, and it was not much more expensive to buy a whole distributor, so he replaced the whole thing. He also put in a new MAP sensor, although he said the store gave him the wrong sensor. I looked up the sensor and the part number appears incorrect, although it seems like the engine should at least start and run poorly. The truck sat for about a year, although he said he had it running six months ago, but if he attached the vacuum hose to the MAP sensor it would run badly. The guys he got the truck from were apparently trying to fix it. On the seat are packages from new relays, cap and rotor, and spark plugs. Neither previous owner ever connected a code reader.

I've siphoned the old gas and put new gas in the tank, confirmed that the spark plug wires are in the correct order and have spark, and confirmed that the fuel pump relay clicks when you turn the key, or at least I think that's which relay it is. I'm not sure if I have adequate fuel pressure, though. Poking the valve in the fuel line behind the injector rail yields a small dribble. Is it supposed to have enough pressure to shoot gasoline out vigorously? I can connect a fuel pressure gauge if necessary. The seller said he suspected the fuel pressure regulator, but never really gave a reason, so I'm wondering.

I've cranked the engine a fair amount and only got a little bit of sputtering a few times, but it doesn't start. I'm wondering what to start with. Maybe the distributor is off by one tooth, but the seller said he had it running, which presumably would have been after he replaced it. I'm also wondering how loud the fuel pump is on a Ford truck. I'm accustomed to turning on the key in my Dodge and Honda vehicles and hearing a loud bzzzzt from the pump. I'm also accustomed to a pump being either broken or working but not something in between. Is it possible for this pump to be weak?

bisjoe

I can’t help too much, but did have a 1990 Bronco with the 300ci 6. Standing by the rear near the tank, you did hear a fairly loud rapid clicking noise when the key was turned to on, lasting about 5 seconds. My fuel pump went out at about 120k miles, just died going down the road. I knew what it was because no more clicking.

Steve83

That's not much info for us to go on to help you. Click this, read the caption, and put ALL the details into your signature so we can see them with each of your posts:


(phone app link)1) The engine doesn't need to run to pull codes;
2) Code readers are notoriously UNreliable for these trucks. I recommend you return it for refund ASAP, and follow the instructions for a jumper wire (paperclip, etc.) in this caption:


(phone app link)No, there are 2 distinct types of MAP. Although they look identical, they work VERY differently, and an EEC built for one won't be able to use the signal from the other. All '87-95 F-series/Bronco (& many other Ford/L/M products of that era) use the same MAP, so collect a few spares at the local JYs.Gas takes ~4 years to go bad. I've checked a few times. Then you haven't confirmed anything. Use a digital multimeter (DMM) to measure DC Volts at the fuel tank connector.


(phone app link)

This explains what to do if either relay is bad or even suspicious:


(phone app link)Yes, that's the ONLY way to check fuel pressure.


(phone app link)It's easy to check without any equipment.


(phone app link)This caption explains how to stab the distributor:


(phone app link)Noise is not an accepted or reliable test for fuel pumps. Some are nearly-silent; others are annoyingly loud.There's more than just the pump involved, so low pressure can't immediately be blamed on the pump. The '90-04 FDM has some known weaknesses in its design & construction. Read this & the NEXT caption:


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woogasnerk

Sorry for the late reply, I've been a bit busy. I pulled the vacuum line off the FPR, and noted that it smelled like gas. I also looked at all the spark plugs and, though they appear to be relatively new, they're covered in soot. This combined with the fact that the engine won't fire even after I timed it and gave it starting fluid is leading me to believe that it might be getting too much gas.

Steve83

Start by replacing the FPR. Use a wire brush (NO LIQUIDS) to temporarily clean the soot off the plugs. Once you're sure the rich condition is fixed, replace the plugs (I recommend MotorCraft from Amazon).

woogasnerk

That sounds like a pretty good idea. As soon as it stops raining here, I'm going to go out and try to run the thing on starting fluid with the fuel pump relay unplugged to see if it's really getting too much gas. Based on the results of that experiment, I'll probably end up ordering a new FPR today.

woogasnerk

I connected a fuel pressure gauge and it said zero, so I jumped the wires in the diagnostic port to force the fuel pump on. It turned on and pumped up to 30 psi. The engine started but it runs poorly, which is why the former owners were messing around with it in the first place. That's an issue to address after the fuel pump issue is solved.

There are two identical relays next to the diagnostic port. Both of them seem to be functioning. One clicks when the key is turned on. The other clicks when the pump is forced by jumping the diagnostic port pins. However, the pump never turns itself on as it is supposed to without being forced. So the next mystery is to figure out what part of the system is failing to turn the pump on.

One other detail: The rear tank goes to 30 PSI and stops. The front tank got up to 60.

Steve83

Unless you have a way to calculate the correct amount of ether to spray in for each cylinder as the engine is running, and then spray exactly that amount, your test won't show anything useful. You KNOW the FPR is leaking - why wouldn't you replace it first?

This caption explains the most-likely reason the FP relay is misbehaving:


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Eric Kleven

I think the FPR spec on those engines was 49psi. Sounds like you have a bum rear pump.