88 mazda rx7 wont run

255

Asked by Brian Oct 26, 2010 at 08:35 PM about the 1988 Mazda RX-7

Question type: Maintenance & Repair

won't run for more then 20 seconds, and only off of ether at that. all starting and fuel system sensors check out good. any ideas?

17 Answers

9,655

Have you checked your fuel pump for power and fuelflow, replaced the fuel filter and checked idle settings? It sounds to me like the car's only running on the accelerated warmup system and stalls when that is turned off, this could indicate insufficient fuel supply..

1 people found this helpful.
255

the fuel filter aint clogged and the pump is able to pressurize the system. is it possible that the pump just can't keep up?

9,655

Check the voltage at the pump, it should be about 12 volts, if not you might try running a power lead directly from the battery to the pump to see if that cures the running issue. In that case a fuel pump rewire might be the best way to go as explained on http://www.1300cc.com/howto/how2/rewire.htm Also check under the car for kinks or dents in the fuel lines which could restrict fuel flow.

255

not yet. workin on it though, slowly but surely. i'll post with updates

15

check your starter solenoid and alternator and the main harness for any shorts in the wires

255

update. fuel pump is good. fuel delivery is good. starting system is good. fires off and everything. why won't she run? although, when she fires it sounds like theres a really bad back fire, or wants to backfire. can't tell for sure cause she aint running. ideas?

9,655

Does it smell of unburnt fuel out of the exhauts? If so check your injectors for leaking. Also check the ignition, starting off with the spark plugs (colour and electrode wear, replacing them if they seem dirty is a good idea anyway) then the plug leads (cracks and signs of arcing are a good sign that they need replacing). The coils are fairly bulletproof so they're not likely to be the culprit. Another possible cause you may want to check for is a failing coolant or intake temperature sensor, if either gives a weird reading the ECU might mess up the fuel dosage. Or in the worst case you might want to check the AFM and the BAC valve.

1 people found this helpful.
255

theres no strong smell of fuel out of the exhaust. i already checked the resistance on the injectors and replace the o-rings while i was at it. spark plugs was actually the first thing i did. the first set was just old, no abnormal wear and are prolly still good. i bought a new set though just in case. i did check resistance on the leading coil pack. book says there should .1 ohms, there wasn't any resistance. didn't think to check coolant sensor and whatnot though. i'll see if those check out good

105

ok so when a rotary is started up after 20-30 secconds it the elapsed time for it to gain oil pressure(u should know that) ok and if it doesnt smell like unburnt fuel something is wrong these cars run rich by default(duh help lubricate and cool) so he might not be getting enough fuel pressure

1 people found this helpful.
9,655

There's rich and then there's RICH, the difference being in a subtle smell of unburnt petrol of great big wafts of fuel vapour coming out the exhaust. Maybe you missed reading the topic as it is cutting out after 20-30 seconds, nothing to do with oil pressure. By the way if it took 20-30 seconds for my TII to get up to pressure I'd start thinking about rebuilding my oil pump, 10 seconds tops is much more realistic on a good pump. As for lubricating... Petrol does NOT lubricate, if you want that go for premix with two-stroke oil or get a diesel engine. It is however very good at diluting and dissolving lubricants, which is why you need to change your engine oil when you get fuel contamination in your engine oil (flooded engines for instance).

255

update. A guy came by and looked at. He says that the fuel system is good. Its just the mass air flow meter/sensor thats bad. its not reading anything and not telling the computer to give any fuel sense theres therotically no air moving to pick up and mix with the fuel. i'mma see if theres a test i can do on the sensor. in the mean time. does this make sense? it does to me, but i'm not too familiar with EFI systems, carburetor are way easier for me.

55

i have an 86 rx7 shell long island ny, cheap and did u ever run an compression test and see if its flooded

255

I actually have it listed on craigslist. I strictly deal locally with cars. I don't really want to sell it though, I love workin on stuff like that too mcuh. Especially to sell before I'm done workin on it. I enjoy fiddlin and learning about stuff like this too much.

215

it does make good sense. i would have to check about the 20~30sec shutdown if that is the problem. but for now, sounds like that may be it. please update though, enjoyable reading

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