QuestionQUESTION: I recently purchased a new fuel pump for my MKIII Spit. The fuel now comes out of the overflow holes and checking the pressure shows 6-7 PSI which seems very high. Is there a way of reducing this pressure or is the pump incorrect?
ANSWER: Hi Mike,
That pressure is too high so you either need to get another lower pressure pump or just put in a fuel pressure regulator and adjust it down to 1 1/2 to 2 1/2 PSI. Regulators are available at most any auto parts stores.
Howard
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QUESTION: Hi Howard
Many thanks for the answer. Since asking the question I have been told that putting a spacer between the pump and the block will adjust the pressure. Would this be correct - it sounds logical that the pump arm will not be moving so far but I think it may adjust the delivery rather than the pressure? Any comments?
Thanks in advance
Mike
AnswerThat is true mike, If the pump you purchased was suppose to have a spacer and you didn't have one to install. You need to put a fuel pressure gauge in to see what you are doing.
The fuel pump arm is moved by a cam to compress a spring in the pump which draws in new fuel. When the cam lets the arm relax the spring forces the diaphragm against the fuel thus causing the fuel pressure. So when a pump is installed without a spacer when one is required, it over compresses the spring thus making the spring stroke stronger and making higher fuel pressure. The Triumph TR-7 had the same problem. There was an early and late pump for the "7" and one required a spacer and the other didn't. Look on the old pump to see if it had a spacer stuck to it.
If you will go to this web site (The Roadster Factory) you will note that they list three pumps for the Spitfire. Two pumps for the 1500, one with a spacer and one without. If you don't find a spacer on the old pump you should contact The Roadster Factory to see if they can supply one, if that is the problem.
https://secure.zeni.net/trf/trf_desc_results.php
1-800-283-3723
